WO2026003369A1 - Novel phosphine catalysts - Google Patents

Abstract

The present invention primarily relates to a coordination complex obtained or obtainable by a process as defined herein and to a process for producing a coordination complex as defined herein. Moreover, the present invention relates to a coordination complex as defined herein. The present invention further relates to the use of a coordination complex obtained or obtainable according to the process as defined herein or of a coordination complex as defined herein as a catalyst. Finally, the present invention relates to a process, preferably a hydrogen transfer reaction, more preferably for the isomerization of a double bond in a substrate, as defined herein.

Description

Novel phosphine catalysts

The present invention primarily relates to a coordination complex obtained or obtainable by a process as defined herein and to a process for producing a coordination complex as defined herein. Moreover, the present invention relates to a coordination complex as defined herein. The present invention further relates to the use of a coordination complex obtained or obtainable according to the process as defined herein or of a coordination complex as defined herein as a catalyst. Finally, the present invention relates to a process, preferably a hydrogen transfer reaction, more preferably for the isomerization of a double bond in a substrate, as defined herein.

Further aspects of the present invention will arise from the description below, in particular from the examples, whereby these are not to be understood as limiting, as well as from the attached patent claims.

In the last decades, noble metal complexes have been used as catalysts due to their high selectivity and superior reactivity. But due to the low relative abundance of and the increasing demand for noble metals like rhodium, ruthenium, iridium or palladium from different industry sectors, earth-abundant transition metals have become more interesting for industrial applications. Especially, the price difference between earth-abundant metals like cobalt, iron and nickel compared to noble metals makes the former interesting for industrial applications. Besides this, earth-abundant metals have a significantly lower toxicity.

Despite the rising demand and the steady academic research for new more sustainable and environmentally friendly catalysts, earth-abundant metal catalysts often show a considerably lower activity and selectivity compared to noble metal catalysts. Therefore, the development of highly efficient earth-abundant metal catalysts is of particularly great interest.

A large number of chemical reactions can be accelerated by homogeneous metal catalysts. The benefit of such metal catalysts is that they lead to better results compared to noncatalyzed reactions. In particular, the use of metal catalysts can achieve higher yields and better selectivities compared to non-catalyzed chemical reactions.

Examples of this include the regioselective hydroformylation of olefins with rhodium catalysts, the asymmetric hydrogenation of olefins or ketones with rhodium or ruthenium complexes or the regio- and chemoselective isomerization of double bonds in olefins.

Homogeneous metal catalysts may contain a metal atom or ion and one or more ligand(s) that is/are coordinated to the central atom. Due to their steric effects and electronic properties, the ligand(s) has/have a major influence on the reactivity and selectivity of the catalyst. Through targeted ligand synthesis, for example, the yield of the target product can be significantly increased.

The catalytic isomerization of double bonds in olefins is a highly efficient method in organic chemistry. The implementation is characterized by a high atom economy and has therefore attracted great interest both in academic research and in industrial applications due to its sustainable character. Recently, catalysts with transition metals such as iron, cobalt or nickel have attracted particular attention, as they are significantly more sustainable than rare earth metals due to their better availability, and because of their low costs. The following publications provide good overviews on this topic: "Base-metal-catalyzed Olefin Isomerization Reaction", X. Liu, B. Li, Q. Liu, Synthesis 2019, 51, 1293; "Hydride transfer reactions catalyzed by cobalt complexes" W. Ai, R. Zhong, X. Liu, Q. Liu, Chem. Rev. 2019, 119, 2876-2953; "Cobalt-catalyzed isomerization of alkenes", S. Zhang, M. Findlater, Synthesis 2021 , 53 (16), 2787-2797.

In terms of sustainability and saving resources, the catalytic isomerization of double bonds in olefins represents a nearly ideal transformation, because it is an energy efficient and atomically economic redox reaction, which produces no waste output. In this respect, transition metal catalyzed olefin isomerization obeys several rules of the twelve principles of green chemistry at once. In consequence, catalytic isomerization of olefins has attracted great interest both in academic research and industrial applications.

The reaction of molecules with heteroatoms such as nitrogen atoms represents an especially challenging form of isomerization reactions. Numerous noble metal catalysts (especially rhodium catalysts) have been reported for the isomerization of allylamines. Overviews and examples can be found in: Krompiec, S. et al. Coord. Chem. Rev. 2008, 252, 1819; Escoubet, S. et al. Eur. J. Org. Chem. 2005, 3855; Cadierno, V. et al. Inorg. Chim. Acta 2017, 455, 398.

Another even more specific form of isomerizations are reactions wherein the substrate not only contains one or more heteroatoms but also two or more double bonds and only one of the double bonds is to be selectively (regio-)isomerized. The following reaction is a prominent example of this type of reaction (Scheme 1):

Scheme 1 : Reaction of /V,/V-diethylgeranylamine to citronellal enamine

This reaction has high commercial relevance because it is an important key step in a synthetic menthol production process. Particularly challenging in this synthesis is the selective isomerization of only one of the two double bonds present.

Both enantioselective and racemic catalysts have been described for this reaction (see: H. Kumobayashi, S. Akutagawa, S. Otsuka, J. Am. Chem. Soc. 1978, 100, 3949; "Enantioselective isomerization of allylamine to enamine: practical asymmetric synthesis of (-)-menthol by Rh-BINAP catalysts. S. Akutagawa. Top. Catal., 1997, 271-274; "Catalytic Asymmetric Synthesis: Asymmetric Isomerization of Allylamines", I. Ojima (Edt.), Wiley- VCH, 1993, 41-61 ; "Discoveries of the catalysis of Asymmetric Isomerization of Allylamines and its Significance in Science and Industry. S. Otsuka. Acta Chem. Scan., 1996, 50, 353- 360; "Mechanism of the asymmetric isomerization of allylamines to enamines catalyzed by 2,2'-bis(diphenylphosphino)-1 ,1 'binaphthyl-rhodium complexes. R. Noyori et al. J. Am.

Chem. Soc. 1990, 112, 4897-4905).

The experiments published by Kumobayashi et al. (cf. above) have been repeated in order to gain better insights into this topic. However, the obtained yields were drastically lower than reported. According to modern analytics, the second double bond present in the substrate (shown at the bottom of Scheme 1) was also isomerized, and not as intended only the double bond shown at the top of Scheme 1 .

Despite the homogeneous metal catalysts described in the literature, there is still a need for further catalysts, as most of those described so far have significant disadvantages. For example, although the rhodium compounds described in the literature show good enantio- and regioselectivity, they are very sensitive to atmospheric oxygen, water and traces of chemical side components that poison the catalyst. In addition, the availability of rhodium has fallen sharply due to higher demand from other industries, which has led to a significant price increase. Furthermore, many of the literature-known catalysts are limited to simple olefins and cannot isomerize molecules that contain heteroatoms or multiple double bonds. On the other hand, the more readily available cobalt catalysts to date show significantly lower regioselectivity (55%, see below).

It was therefore the primary object of the present invention to provide novel coordination complexes, which represent suitable catalysts, especially for the isomerization of N,N- diethylgeranylamine to citronellal enamine and/or for the conversion of N,N- diethylgeranylamine to citronellal. Such novel catalysts preferably provide superior conversion and selectivity rates compared to catalysts known from the literature for this process. Thereby, preferably a better contribution to green chemistry shall be achieved. Furthermore, high turnover numbers for the isomerization process shall be obtained.

Furthermore, it was an object of the present invention to provide a process for the isomerization of olefins, especially of allylamines to enamines, which preferably proceeds in economically useful or reasonable yields.

Even though coordination complexes based on earth-abundant metals are preferred embodiments according to the present invention, it shall nevertheless also be an object of the present invention to provide novel coordination complexes, which represent suitable catalysts, especially for the isomerization of /V,/V-diethylgeranylamine to citronellal enamine and/or for its conversion to citronellal, that are based on noble metals like for instance Rh, Ru or Ir. Further objects underlying the present invention follow from the description below and the present patent claims.

According to a first aspect of the present invention, the stated object is achieved by a coordination complex or mixture of two or more coordination complexes obtained or obtainable by a process comprising or consisting of the following steps: a) Providing a precursor coordination complex, wherein the coordination centre of the precursor coordination complex is a rhodium, ruthenium, palladium, iridium, manganese, iron, cobalt, or nickel atom or is a rhodium, ruthenium, palladium, iridium, manganese, iron, cobalt, or nickel ion or is a 3d transition metal atom or ion, preferably wherein the coordination centre is a manganese, iron, cobalt, or nickel atom or is a manganese, iron, cobalt, or nickel ion, more preferably wherein the coordination centre is a cobalt atom or ion, more preferably wherein the precursor coordination complex is a cobalt(ll) or cobalt(lll) salt, most preferably wherein the precursor coordination complex is selected from the group consisting of cobalt(ll) acetylacetonate, cobalt(lll) acetylacetonate, cobalt(ll) acetate, cobalt(ll) naphthenate, cobalt(ll) benzoate, cobalt(ll) 2-ethylhexanoate, cobalt(ll) chloride, cobalt(ll) bromide, cobalt(ll) trifluoromethanesulfonate, dibromo(1 ,2- dimethoxyethane)cobalt(ll), bis(1 ,5-cyclooctadiene)dirhodium(l) dichloride, bis(1 ,5- cyclooctadiene)diiridium(l) dichloride, and dichloro(benzene)ruthenium(ll) dimer, and/or preferably wherein one or two or three or more or all of the ligands of the precursor coordination complex is/are (a) bidentate ligand(s), b) providing a compound of formula (I) wherein R¹ is a residue independently selected from, preferably wherein R¹ is a residue selected from, the group consisting of wherein R³, R⁴, and R⁵ are independently selected from the group consisting of H, alkyl, or aryl, and/or R³ forms an aromatic ring with R⁴, preferably a benzene ring, and/or R⁴ forms an aromatic ring with R⁵, preferably a benzene ring, and wherein R² is a residue selected from the group consisting of

or R² is a residue according to formula (II) wherein R³, R⁴, and R⁵ are independently selected from the group consisting of H, alkyl, or aryl, and/or R³ forms an aromatic ring with R⁴, preferably a benzene ring, and/or R⁴ forms an aromatic ring with R⁵, preferably a benzene ring, and preferably wherein

(i.e. all of the residues R¹, R¹ and R² bound to the compound of formula (I) are then the coordination centre of the precursor coordination complex provided in step a) is not a rhodium atom or ion, and/or - in case both of R¹ and R² are

(i.e. all of the residues R¹, R¹ and R² bound to the compound of formula (I) are then the coordination centre of the precursor coordination complex provided in step a) is not a rhodium atom or ion, and/or in case both of R¹ and R² are then the coordination centre of the precursor coordination complex provided in step a) is not a ruthenium atom or ion, and/or in case both of R¹ and R² are then the coordination centre of the precursor coordination complex provided in step a) is not a palladium atom or ion, and/or in case both of R¹ and R² are then the coordination centre of the precursor coordination complex provided in step a) is not a cobalt atom or ion, and/or in case both of R¹ and R² are then the coordination centre of the precursor coordination complex provided in step a) is not a nickel atom or ion, and/or in case both of R¹ and R² are <s 0 kl then the coordination centre of the precursor coordination complex provided in step a) is not an iron atom or ion, and/or in case both of R¹ and R² are then the coordination centre of the precursor coordination complex provided in step a) is not an atom or ion selected from the group consisting of rhodium, palladium, cobalt, nickel, and iron, c) producing a solution or suspension comprising the precursor coordination complex provided in step a), the compound of formula (I) provided in step b), and one or more solvent(s), preferably one or more non-polar solvents), more preferably wherein the one or more solvent(s) is/are selected from the group consisting of tetrahydrofuran, 2-methyltetrahydrofuran, toluene, cyclohexane, benzene, xylene, dibutyl ether, dioxane, hexane, and heptane, d) adding, preferably dropwise or portionwise, one or more reducing agent(s) to the solution or suspension produced in step c), preferably wherein the one or more reducing agent(s) is/are selected from the group consisting of diisobutylaluminium hydride (DIBAL), triethylaluminium, diisobutylaluminium hydride-tetrahydrofuran- solution, diisobutylaluminium hydride-toluene-solution, aluminium hydride (alane), /V,/V-dimethylethylamine complex, lithium diisobutyl-tert-butoxyaluminium hydride, lithium aluminium hydride, sodium borohydride, and sodium triethylborohydride, e) optionally, isolating the one or more coordination complex(es) formed in step d) from the reaction mixture.

According to preferred embodiment according to the present invention, both one or more compounds of formula (I) as defined herein and one or more compounds of formula (IV) as defined herein (cf. further below) are provided in step b) of the process as defined herein. According to another preferred embodiment, the following applies to the coordination complex obtained or obtainable by a process according to the present invention:

In case R¹ is , R² is not or vice versa, and

(i.e. all of the residues R¹, R¹ and R² bound to the compound of formula (I) are then the coordination centre of the precursor coordination complex provided in step a) is not a rhodium atom or ion.

Surprisingly, it was found that the novel coordination complexes according to the invention described herein are suitable for the above mentioned purposes. The compounds of formula (I) and (IV) advantageously provide more electron rich systems resulting in superior conversion and selectivity rates when used as ligands in in the coordination complexes according to the invention for catalytic reactions. Furthermore, high turnover numbers for isomerization processes can be achieved.

Another surprising observation was that monodentate ligands advantageously were more suitable for the formation of novel coordination complexes according to the invention as catalysts, especially for the isomerization of /V,/V-diethylgeranylamine to citronellal enamine and/or for its conversion to citronellal, and which advantageously provide superior conversion and selectivity rates compared to catalysts bearing bi- or tridentate ligands. In the course of the investigations underlying the present invention, it was found that catalysts with (benzo)furyl-decorated phosphine ligands preferably showed the best results for isomerizations of double bonds. However, it should be emphasized that catalysts with bi- or tridentate ligands also provide good results in the context of the present invention.

So far, phosphine ligands have only rarely been described in combination with cobalt as a coordination centre for isomerization reactions, examples of which are "Cobalt-catalyzed asymmetric hydrogenation of ketones: A remarkable additive effect on enantioselectivity", Du et al, Chinese Chemical Leters 2021 , 32, 3, 1241-1244; "Cobalt-Catalyzed, Room- Temperature Addition of Aromatic Imines to Alkynes via Directed C-H Bond Activation", Lee et al, J. Am. Chem. Sec. 2011 , 133, 43, 17283-17295; "Cobalt-Catalyzed Regioselective Carbo-amidation of Alkynes with Imides Enabled by Cleavage of C-N and C-C Bonds", Min et al., Org. Let. 2020, 22, 3386-3391 .

No cobalt complexes with furylphosphine ligands for isomerizations of olefins have been described to date.

Certain furylphosphine ligands have been described in the literature in combination with noble metals, e.g. in a publication in combination with Pd as the coordination centre for use in the Stille coupling: "Large rate accelerations in the Stille reaction with tri-2-furylphosphine and triphenylarsine as palladium ligands: mechanistic and synthetic implications", J. Am. Chem. Soc. 1991 , 113, 9585-9595. The following publications describe other noble metal furylphosphine catalysts: "Rhodium catalyzed hydroboration of terminal alkynes using pinacolborane promoted by Tri(2-furyl)phosphine" Synthesis 2017, 49(12); "2- Furylphosphines as ligands for transition-metal-mediated organic synthesis", N. Andersen, B. Keay, Chem. Rev. 2001 , 101 (4), 997-1030.

For tri(benzofuran-2-yl)phosphine (TBFP), however, only very few publications have been published to date. One example is the publication by C. Santelli-Rouvier, C. Coin, L. Toupet, M. Santelli, Journal of Organometallic Chemistry 1995, 495, 91-96, which only describes the complex chemistry. Significantly, only one example is known to date in which tri(benzofuran-2-yl)phosphine was used in a catalytic reaction ("A highly efficient procedure for hydroformylation and hydroamino-vinylation of methyl acrylate", M. L. Clarke and G. J. Roff, Green Chem., 2007, 9, 792-796).

Since 1980, tri(furan-2-yl)phosphine (TFP) has been used in palladium catalyzed crosscoupling reactions due to its exceptional chemical properties as a relatively poor o-donor and less bulky ligand. In many cases, the TFP ligand allows to perform cross-coupling reactions with higher selectivity and under milder reaction conditions than triphenylphosphine.

To date, furylphosphine ligands have regularly been described with noble metals, while cobalt furylphosphine complexes have been less investigated. Previous publications disclosing cobalt furylphosphine catalysts mainly used the standard tri(furan-2- yl)phosphine ligand (cf. Scheme 2). Accordingly, the new coordination complexes according to the present invention satisfy the ongoing demand for new catalysts for research and industrial applications.

T ri(benzofuran-2-yl)phosphine

Scheme 2: Chemical structures of tri(furan-2-yl)phosphine and tri(benzofuran-2- yl)phosphine

Applicant is only aware of one publication where tri(benzofuran-2-yl)phosphine is used as a ligand for rhodium catalyzed hydroformylation and hydroamino-vinylation of methyl acrylates. Furthermore, also bis-benzofuran-phosphine compounds have hardly been described in the literature. Based on the very limited number of publications on benzofuran phosphines, it was particularly surprising to find the new coordination complexes according to the present invention bearing compounds of formula (I) and/or (IV).

In general, the coordination complexes according to the present invention comprising one, two, three, four or more compound(s) of formula (I) and/or (IV) can be used as catalysts in catalytic reactions in the form of isolated coordination complexes (i.e. having been isolated after their synthesis) or as in situ generated coordination complexes (i.e. not having been isolated after their synthesis). From an industrial perspective, in situ generated catalysts have several advantages for large scale applications compared to the use of isolated catalysts. The production of isolated catalysts takes a considerable amount of time and leads to increased chemical waste, likewise isolated catalysts are much more unstable against atmospheric oxygen and water. In comparison, the handling of precursors and the compounds of formula (I) and/or (IV) for the in situ generation of coordination complexes according to the present invention is generally less challenging (cf. the processes described further below).

New in situ generated coordination complexes according to the invention comprising, for instance, a cobalt atom or ion as a coordination centre can be generated from a cobalt precursor complex, for example a cobalt(ll) salt or a cobalt(lll) salt as described in step a) of the process according to the invention. The in situ generated coordination complexes according to the present invention comprising a cobalt atom or ion as a coordination centre can be generated, for instance, by the addition of a reducing agent to the cobalt(ll) or cobalt(lll) precursor in the presence of one or more compound(s) of formula (I) and/or (IV) according to the present invention, which preferably initially generates coordination complexes according to the invention with Co(l) as a coordination centre (cf. step d) of the production processes according to the present invention). This/these Co(l) species may further react to form coordination complexes according to the invention with Co(0) as a coordination centre.

Only two cobalt catalysts that were able to catalyze the isomerization of N,N- diethylgeranylamine to citronellal enamine have been reported by Noyori et al. in 1978, the cobalt nitrogen complex HCo(N)2(PPfi3)3 and a cobalt in situ system obtained from a cobalt(ll) salt with AIEts or DIBAL-H as reducing agent and triphenylphosphine (with the ratio 1 :3:3). In contrast to the above described rhodium catalyst from Takasago, these cobalt catalysts show significantly lower activity and regioselectivity for the isomerization of /V,/V-diethylgeranylamine to citronellal enamine (85% yield). In addition, the required high catalyst loading is a major disadvantage for an industrial application of these cobalt catalysts.

Moreover, literature-known earth-abundant transition metal catalysts, that are suitable for isomerization reactions, often suffer from elaborate ligand synthesis procedures, which include several synthesis steps. In addition, these earth-abundant transition metal catalysts usually have higher substrate limitations compared to noble metal catalysts. Thus, the process for producing a coordination complex according to the present invention is particularly advantageous for overcoming these issues.

Catalytic test reactions carried out during the studies underlying the present invention revealed that active coordination complexes according to the invention with Co(l) as a coordination centre are formed in the presence of one as well as two or three equivalents of the compound(s) of formula (I) and/or (IV) according to the invention during step d) of the process, whereby the presence of more than three equivalents of the compound(s) of formula (I) and/or (IV) in step d) of the process may in a few cases lead to a deactivation of the coordination complexes. The low required molar ratio of the compound(s) of formula (I) and/or (IV) to the cobalt precursor coordination complex is a major advantage of the in situ generated coordination complexes according to the present invention in terms of industrial application, because in situ systems often use high molar ratios of phosphine ligands.

Interestingly, it was observed in crystallization experiments that the in situ generated coordination complexes according to the invention with Co(l) as a coordination centre can disproportionate, preferably forming coordination complexes according to the invention with Co(0) as a coordination centre with four coordinating compounds of formula (I) (and/or (IV)) as defined herein as ligands.

Advantageously, the in situ generated coordination complexes according to the invention, especially the ones with Co atoms or ions, preferably Co(0) or Co(l), as coordination centres are highly active catalysts. Several different active species of the coordination complexes according to the invention may be formed in solution by the process according to the invention. One, two, three, four or more further ligand(s) selected from the group consisting of H, solvent molecules and ligands of the precursor coordination complex can optionally also be bound to the coordination centres of the coordination complexes obtained by the process according to the invention by one, two or more coordinative bond(s), respectively.

According to a preferred embodiment of the present invention, the alkyl residue(s) in formula (II) is/are selected from the group consisting of methyl, ethyl, propyl, and butyl, and/or the aryl residue(s) in formula (II) is/are selected from the group consisting of phenyl and benzyl.

Furthermore, according to a preferred embodiment of the compound of formula (I) as defined herein, R¹ and R² are the same. According to another preferred embodiment of the compound of formula (I) as defined herein, R¹ and R² are different from one another. According to another preferred embodiment of the compound of formula (I) as defined herein, both R¹ residues are the same.

Preferably, the solvents used in step c) are anhydrous solvents. Preferably, the one or more coordination complex(es) according to the invention is/are generated in situ by process steps a) to d) as defined herein and immediately used as catalyses) without any further purification or isolation steps.

If the precursor coordination complex provided in step a) and/orthe compound(s) of formula (I) and/or (IV) provided in step b) of the process as defined herein is/are already dissolved in or mixed with one or more solvent(s), preferably one or more non-polar solvent(s), more preferably one or more solvent(s) selected from the group consisting of tetrahydrofuran, 2- methyltetrahydrofuran, toluene, cyclohexane, benzene, xylene, dibutyl ether, dioxane, hexane and heptane, then step c) of the process as defined herein may only encompass the mixing of said components to produce a solution or suspension as defined in step c).

Preferably, at least steps c) and d) of the process as defined herein are carried out under an inert gas, preferably an argon, atmosphere. More preferably, steps a) to d) or steps a) to e), if step e) is present, are carried out under an inert gas, preferably an argon, atmosphere.

Preferably, the precursor coordination complex provided in step a) and the compound(s) of formula (I) and/or (IV) provided in step b) are mixed together in solid form, preferably under an inert gas, more preferably an argon, atmosphere, before the one or more solvent(s) (as defined herein) are added in step c) of the process as defined herein.

According to a preferred embodiment of the coordination complex obtained or obtainable by a process according to the present invention, the precursor coordination complex provided in step a) is selected from the group consisting of cobalt(ll) acetylacetonate, cobalt(lll) acetylacetonate, cobalt(ll) acetate, cobalt(ll) naphthenate, cobalt(ll) benzoate, cobalt(ll) 2-ethylhexanoate, cobalt(ll) chloride, cobalt(ll) bromide, cobalt(ll) trifluoromethanesulfonate, dibromo(1 ,2-dimethoxyethane)cobalt(ll), bis(1 ,5- cyclooctadiene)dirhodium(l) dichloride, bis(1 ,5-cyclooctadiene)diiridium(l) dichloride, and dichloro(benzene)ruthenium(ll) dimer.

A preferred embodiment according to the present invention is a coordination complex obtained or obtainable by a process as defined herein, wherein the compound of formula (I) provided in step b) is selected from the group consisting of

The compound(s) of formula (I) as defined above are particularly advantageous in the context of the present invention as they give high conversion rates in catalytic reactions when used as ligands in coordination complexes according to the present invention.

Another preferred embodiment according to the present invention is a coordination complex obtained or obtainable by a process as defined herein, wherein the compound of formula (I) provided in step b) is selected from the group consisting of

According to another preferred embodiment of the present invention, a coordination complex is obtained or obtainable by a process as defined herein, wherein the molar ratio of the compound(s) of formula (I) and/or (IV), preferably of the compound of formula (I), to the precursor coordination complex in the solution or suspension produced in step c) is in a range of from 1 to 10, preferably from 1 to 5, more preferably is equal to or greater than 1.

According to a preferred embodiment of the present invention, the molar ratio of the precursor coordination complex to the compound(s) of formula (I) and/or (IV) as defined herein refers the number of coordination centres of the precursor coordination complex to the number of compounds of formula (I) and/or (IV) present in the solution or suspension produced in step c).

Another preferred embodiment of the present invention is a coordination complex obtained or obtainable by a process as defined herein, wherein the concentration of the precursor coordination complex in the solution or suspension produced in step c) is in a range of from 0.01 to 15 mol%, preferably from 0.01 to 10 mol%, more preferably from 0.01 to 5 mol%, more preferably 0.01 to 0.5 mol%, most preferably from 0.05 to 0.1 mol%.

According to another preferred embodiment of the coordination complex obtained or obtainable by a process according to the present invention, the concentration of the precursor coordination complex in the solution or suspension produced in step c) is about 5 mol%, if the coordination centre of the precursor coordination complex is a noble metal, e.g. is a rhodium, ruthenium, palladium, or iridium atom or ion.

According to another preferred embodiment of the coordination complex obtained or obtainable by a process according to the present invention, the concentration of the precursor coordination complex in the solution or suspension produced in step c) is about 10 mol%, if the coordination centre of the precursor coordination complex is not a noble metal, e.g. is a manganese, iron, cobalt, or nickel atom ion.

A further preferred embodiment of the present invention is a coordination complex obtained or obtainable by a process as defined herein, wherein the concentration of the compound(s) of formula (I) and/or (IV) in the solution or suspension produced in step c) is in a range of from 0.1 to 25 mol%, preferably 0.1 to 20 mol%, more preferably from 0.1 to 10 mol%, more preferably from 0.1 to 5 mol%, more preferably from 0.5 to 3 mol%, most preferably from 1 to 3 mol%.

According to another preferred embodiment of the coordination complex obtained or obtainable by a process according to the present invention, the concentration of the compound(s) of formula (I) and/or (IV) in the solution or suspension produced in step c) is about 10 mol%, if the the coordination centre of the precursor coordination complex is a noble metal, e.g. is a rhodium, ruthenium, palladium, or iridium atom or ion.

According to another preferred embodiment of the coordination complex obtained or obtainable by a process according to the present invention, the concentration of the compound(s) of formula (I) and/or (IV) in the solution or suspension produced in step c) is about 20 mol%, if the the coordination centre of the precursor coordination complex is a not noble metal, e.g. is a manganese, iron, cobalt, or nickel atom ion.

Furthermore, according to a preferred embodiment of the process according to the invention, the concentration of the reducing agent in the reaction mixture obtained in step d) preferably is in a range of from 0.1 to 25 mol%, preferably from 0.1 to 20 mol%, more preferably from 0.1 to 10 mol%, more preferably from 0.1 to 4 mol%, more preferably from 0.5 to 3 mol%, most preferably from 1 to 2 mol%.

According to another preferred embodiment of the coordination complex obtained or obtainable by a process according to the present invention, the concentration of the reducing agent in the reaction mixture obtained in step d) is about 10 mol%, if the coordination centre of the precursor coordination complex is a noble metal, e.g. is a rhodium, ruthenium, palladium, or iridium atom or ion.

According to another preferred embodiment of the coordination complex obtained or obtainable by a process according to the present invention, the concentration of the reducing agent in the reaction mixture obtained in step d) is about 20 mol%, if the the coordination centre of the precursor coordination complex is not a noble metal, e.g. is a manganese, iron, cobalt, or nickel atom ion.

Another preferred embodiment of the present invention is a coordination complex obtained or obtainable by a process as defined herein, wherein step d) is carried out at a temperature in the range of from 0 to 150 °C, preferably in the range of from 15 to 125 °C, more preferably in the range of from 25 to 120 °C.

According to a second aspect of the present invention, the stated object is achieved by a process for producing a coordination complex, preferably as defined herein, comprising or consisting of the following steps: a) Providing a precursor coordination complex, wherein the coordination centre of the precursor coordination complex is a rhodium, ruthenium, palladium, iridium, manganese, iron, cobalt, or nickel atom or is a rhodium, ruthenium, palladium, iridium, manganese, iron, cobalt, or nickel ion or is a 3d transition metal atom or ion, preferably wherein the coordination centre is a manganese, iron, cobalt, or nickel atom or is a manganese, iron, cobalt, or nickel ion, more preferably wherein the coordination centre is a cobalt atom or ion, more preferably wherein the precursor coordination complex is a cobalt(ll) or cobalt(lll) salt, most preferably wherein the precursor coordination complex is selected from the group consisting of cobalt(ll) acetylacetonate, cobalt(lll) acetylacetonate, cobalt(ll) acetate, cobalt(ll) naphthenate, cobalt(ll) benzoate, cobalt(ll) 2-ethylhexanoate, cobalt(ll) chloride, cobalt(ll) bromide, cobalt(ll) trifluoromethanesulfonate, dibromo(1 ,2- dimethoxyethane)cobalt(ll), bis(1 ,5-cyclooctadiene)dirhodium(l) dichloride, bis(1 ,5- cyclooctadiene)diiridium(l) dichloride, and dichloro(benzene)ruthenium(ll) dimer, and/or preferably wherein one or two or three or more or all of the ligands of the precursor coordination complex is/are (a) bidentate ligand(s), b) providing a compound of formula (I) wherein R¹ is a residue independently selected from, preferably wherein R¹ is a residue selected from, the group consisting of wherein R³, R⁴, and R⁵ are independently selected from the group consisting of H, alkyl, or aryl, and/or R³ forms an aromatic ring with R⁴, preferably a benzene ring and/or R⁴ forms an aromatic ring with R⁵, preferably a benzene ring, and wherein R² is a residue selected from the group consisting of or R² is a residue according to formula (II) wherein R³, R⁴, and R⁵ are independently selected from the group consisting of H, alkyl, or aryl, and/or R³ forms an aromatic ring with R⁴, preferably a benzene ring, and/or R⁴ forms an aromatic ring with R⁵, preferably a benzene ring, and preferably wherein in case R¹ is , R² is not or vice versa, and/or in case R¹ is , R² is not or vice versa, and/or then the coordination centre of the precursor coordination complex provided in step a) is not a rhodium atom or ion, and/or in case both of R¹ and R² are then the coordination centre of the precursor coordination complex provided in step a) is not a rhodium atom or ion, and/or in case both of R¹ and R² are then the coordination centre of the precursor coordination complex provided in step a) is not a ruthenium atom or ion, and/or in case both of R¹ and R² are then the coordination centre of the precursor coordination complex provided in step a) is not a palladium atom or ion, and/or in case both of R¹ and R² are then the coordination centre of the precursor coordination complex provided in step a) is not a cobalt atom or ion, and/or in case both of R¹ and R² are then the coordination centre of the precursor coordination complex provided in step a) is not a nickel atom or ion, and/or in case both of R¹ and R² are then the coordination centre of the precursor coordination complex provided in step a) is not an iron atom or ion, and/or in case both of R¹ and R² are then the coordination centre of the precursor coordination complex provided in step a) is not an atom or ion selected from the group consisting of rhodium, palladium, cobalt, nickel, and iron, c) producing a solution or suspension comprising the precursor coordination complex provided in step a), the compound of formula (I) provided in step b), and one or more solvent(s), preferably one or more non-polar solvents), more preferably wherein the one or more solvent(s) is/are selected from the group consisting of tetrahydrofuran, 2-methyltetrahydrofuran, toluene, cyclohexane, benzene, xylene, dibutyl ether, dioxane, hexane, and heptane, d) adding, preferably dropwise or portionwise, one or more reducing agent(s) to the solution produced in step c), preferably wherein the one or more reducing agent(s) is/are selected from the group consisting of diisobutylaluminium hydride (DIBAL), triethylaluminium, diisobutylaluminium hydride-tetrahydrofuran-solution, diisobutylaluminium hydride-toluene-solution, aluminium hydride (alane), N,N- dimethylethylamine complex, lithium diisobutyl-tert-butoxyaluminium hydride, lithium aluminium hydride, sodium borohydride, and sodium triethylborohydride, and e) optionally, isolating the one or more coordination complex(es) formed in step d) from the reaction mixture.

Preferably, the solvents used in step c) are anhydrous solvents.

According to preferred embodiment according to the present invention, both one or more compounds of formula (I) as defined herein and one or more compounds of formula (IV) as defined herein (cf. further below) are provided in step b) of the process according to the invention.

What has been stated herein in terms of the preferred embodiments of the first aspect applies accordingly to the preferred embodiments of the second aspect and vice versa.

A preferred embodiment according to the present invention is a process as defined herein, wherein the compound of formula (I) is selected from the group consisting of

L30

Another preferred embodiment of the present invention is a process as defined herein, wherein the molar ratio of the compound(s) of formula (I) and/or (IV) (cf. further below), preferably of the compound of formula (I), to the precursor coordination complex in the solution produced in step c) is in a range of from 1 to 10, preferably from 1 to 5, more preferably is equal to or greater than 1 . According to a third aspect of the present invention, the stated object is achieved by a coordination complex, preferably obtained or obtainable according to a process as defined herein, wherein one, two, three, four or more of the compounds of formula (I) and/or (IV) as defined herein are bound as ligand(s) to the one, two or more coordination centre(s) of the coordination complex by one, two or more coordinative bond(s), respectively, and optionally wherein one, two, three, four or more further ligand(s) selected from the group consisting of H, solvent molecules and ligands of a precursor coordination complex are bound to the one or more coordination centre(s) of the coordination complex by one, two or more coordinative bond(s), respectively.

The process as defined herein leads to the in situ generation of a mixture of coordination complexes as defined herein.

Another preferred embodiment of the present invention is a coordination complex as defined herein, wherein the coordination centre(s) of the coordination complex is/are (a) rhodium, ruthenium, palladium, iridium, manganese, iron, cobalt, or nickel atom(s) or is/are (a) rhodium, ruthenium, palladium, iridium, manganese, iron, cobalt, or nickel ion(s) or is/are (a) 3d transition metal atom(s) or ion(s), preferably wherein the coordination centre(s) is/are (a) manganese, iron, cobalt, or nickel atom(s) or is/are (a) manganese, iron, cobalt, or nickel ion(s), more preferably wherein the coordination centre(s) is/are (a) cobalt atom(s) or ion(s), most preferably is/are (a) Co(0) atom(s) or (a) Co(l), Co(ll) or Co(lll) ion(s).

Another preferred embodiment of the present invention is a coordination complex as defined herein, wherein the one or more solvent molecule(s) that is/are bound to the coordination centre(s) of the coordination complex by one, two or more coordinative bond(s), respectively, (if applicable) is/are one or more non-polar solvent molecule(s), preferably is/are selected from the group consisting of tetrahydrofuran, 2- methyltetrahydrofuran, toluene, cyclohexane, benzene, xylene, dibutyl ether, dioxane, hexane, and heptane.

Another preferred embodiment of the present invention is a coordination complex as defined herein, wherein the one or more ligand(s) of the precursor coordination complex that is/are bound to the coordination centre(s) of the coordination complex by one, two or more coordinative bond(s), respectively, (if applicable) is/are bidentate ligand(s), preferably is/are selected from the group consisting of acetylacetonate, acetate, naphthenate, benzoate, 2-ethylhexanoate, chloride, bromide, trifluoromethanesulfonate, 1 ,2- dimethoxyethane, 2,2,6,6-tetramethyl-3,5-heptanedionate, hexafluoroacetylacetonate, and trifluoroacetylacetonate. According to a fourth aspect of the present invention, the stated object is achieved by a coordination complex according to formula (Illa), (I II b) or (II Ic)

(Illa) (lllb) (lllc) wherein M is the coordination centre of the coordination complex, wherein the coordination centre of the coordination complex is a rhodium, ruthenium, palladium, iridium, manganese, iron, cobalt, or nickel atom or is a rhodium, ruthenium, palladium, iridium, manganese, iron, cobalt, or nickel ion or is a 3d transition metal atom or ion, preferably wherein the coordination centre is a manganese, iron, cobalt, or nickel atom or is a manganese, iron, cobalt, or nickel ion, more preferably wherein the coordination centre is a cobalt atom or ion, most preferably is a Co(0) atom or a Co(l), Co(ll) or Co(lll) ion, and wherein the residues R⁶ to R¹¹, if present, are connected to the coordination centre via coordinative bonds, and wherein one compound of formula (I) or (IV) as defined herein represents one or two of the residues R⁶ to R¹¹, if present, and wherein in case the compound of formula (I) or (IV) binds via one coordinative bond to the coordination centre, it represents one of the residues, and wherein in case the compound of formula (I) or (IV) binds via two coordinative bonds to the coordination centre (chelate), it represents two of the residues, and wherein the remaining residues, if present, preferably are selected from the group consisting of H, solvent molecules, and ligands of a precursor coordination complex.

Preferably, the ligands of the precursor coordination complex, if present, bind to the coordination centre via one or two coordinative bonds. According to a fifth aspect of the present invention, the stated object is achieved by a coordination complex according to formula (Illa), (I II b) or (II Ic)

(Illa) (I I lb) (I lie) wherein M is the coordination centre of the coordination complex, wherein the coordination centre of the coordination complex is a rhodium, ruthenium, palladium, iridium, manganese, iron, cobalt, or nickel atom or is a rhodium, ruthenium, palladium, iridium, manganese, iron, cobalt, or nickel ion or is a 3d transition metal atom or ion, preferably wherein the coordination centre is a manganese, iron, cobalt, or nickel atom or is a manganese, iron, cobalt, or nickel ion, more preferably wherein the coordination centre is a cobalt atom or ion, most preferably is a Co(0) atom or a Co(l), Co(ll) or Co(lll) ion, and wherein the residues R⁶ to R¹¹, if present, are connected to the coordination centre via coordinative bonds, and wherein two compounds of formula (I) and/or (IV) as defined herein represent two, three, four or more of the residues R⁶to R¹¹, if present, and wherein in case a compound of formula (I) or (IV) binds via one coordinative bond to the coordination centre, it represents one of the residues, and wherein in case a compound of formula (I) or (IV) binds via two coordinative bonds to the coordination centre (chelate), it represents two of the residues, and wherein the remaining residues, if present, preferably are selected from the group consisting of H, solvent molecules, and ligands of a precursor coordination complex.

A preferred embodiment ofthe present invention, especially in the context of the previously described aspect, is a coordination complex according to formula (Illa) as described above, wherein M is a cobalt atom or ion, preferably a Co(l) ion, and wherein two compounds bind to the coordination centre via one coordinative bond, respectively, i.e. represent two of the residues R⁶to R¹¹, and wherein the remaining residues preferably are selected from the group consisting of H, solvent molecules, preferably THF, and ligands of a precursor coordination complex, preferably acetylacetonate.

Another preferred embodiment of the present invention, especially in the context of the previously described aspect, is a coordination complex according to formula (lllc) as described above, wherein M is a cobalt atom or ion, preferably a cobalt (0) atom, and wherein two compounds bind to the coordination centre via one coordinative bond, respectively, i.e. represent two of the residues R⁶ to R⁹, and wherein the remaining residues preferably are solvent molecules, preferably are THF.

According to a sixth aspect of the present invention, the stated object is achieved by a coordination complex according to formula (Illa), (I II b) or (lllc) wherein M is the coordination centre of the coordination complex, wherein the coordination centre of the coordination complex is a rhodium, ruthenium, palladium, iridium, manganese, iron, cobalt, or nickel atom or is a rhodium, ruthenium, palladium, iridium, manganese, iron, cobalt, or nickel ion or is a 3d transition metal atom or ion, preferably wherein the coordination centre is a manganese, iron, cobalt, or nickel atom or is a manganese, iron, cobalt, or nickel ion, more preferably wherein the coordination centre is a cobalt atom or ion, most preferably is a Co(0) atom or a Co(l), Co(ll) or Co(lll) ion, and wherein the residues R⁶ to R¹¹, if present, are connected to the coordination centre via coordinative bonds, and wherein three compounds of formula (I) and/or (IV) as defined herein represent three or more of the residues R⁶ to R¹¹, if present, and wherein in case a compound of formula (I) or (IV) binds via one coordinative bond to the coordination centre, it represents one of the residues, and wherein in case a compound of formula (I) or (IV) binds via two coordinative bonds to the coordination centre (chelate), it represents two of the residues, and wherein the remaining residues, if present, preferably are selected from the group consisting of H, solvent molecules, and ligands of a precursor coordination complex.

According to a seventh aspect of the present invention, the stated object is achieved by a coordination complex according to formula (Illa), (I II b) or (II Ic)

(Illa) (lllb) (lllc) preferably a coordination complex according to formula (Illa) or (lllc), wherein M is the coordination centre of the coordination complex, wherein the coordination centre of the coordination complex is a rhodium, ruthenium, palladium, iridium, manganese, iron, cobalt, or nickel atom or is a rhodium, ruthenium, palladium, iridium, manganese, iron, cobalt, or nickel ion or is a 3d transition metal atom or ion, preferably wherein the coordination centre is a manganese, iron, cobalt, or nickel atom or is a manganese, iron, cobalt, or nickel ion, more preferably wherein the coordination centre is a cobalt atom or ion, most preferably is a Co(0) atom or a Co(l), Co(ll) or Co(lll) ion, and wherein the residues R⁶ to R¹¹, if present, are connected to the coordination centre via coordinative bonds, and wherein four compounds of formula (I) and/or (IV) as defined herein represent four or more of the residues R⁶ to R¹¹, if present, and wherein in case a compound of formula (I) or (IV) binds via one coordinative bond to the coordination centre, it represents one of the residues, and wherein in case a compound of formula (I) or (IV) binds via two coordinative bonds to the coordination centre (chelate), it represents two of the residues, and wherein the remaining residues, if present, preferably are selected from the group consisting of H, solvent molecules, and ligands of a precursor coordination complex.

A preferred embodiment ofthe present invention, especially in the context of the previously described aspect, is a coordination complex according to formula (lllc) as described above, wherein M is a cobalt atom or ion, preferably a Co(0) atom, and wherein four compounds bind to the coordination centre via one coordinative bond, respectively, i.e. represent all four of the residues R⁶ to R⁹.

Preferred embodiments of the third aspect of the present invention also are preferred embodiments of the fourth, fifth, sixth and seventh aspect of the present invention and vice versa.

According to an eighth aspect of the present invention, the stated object is achieved by using a coordination complex obtained or obtainable according to a process as defined herein or by using a coordination complex as defined herein as a catalyst, preferably in a hydrogen transfer reaction, more preferably for the (regio-)isomerization of a double bond in a substrate and/or for the conversion of a substrate into another compound.

When a substrate comprises two or more double bonds, it is particularly challenging to selectively manipulate the position of only one of the double bonds in the molecule by catalytic reaction. Advantageously, the coordination complexes according to the present invention enable the catalysis of (regio-)isomerization reactions, wherein the position of only one of the double bonds in a substrate comprising two or more double bonds is selectively changed (cf. below for further details).

Thus, another preferred embodiment of the present invention is a use as defined herein, wherein the substrate to be isomerized comprises one, two or more double bonds, preferably comprises two or more double bonds, preferably wherein only one of the double bonds is (regio-)isomerized.

Another preferred embodiment of the present invention is a use as defined herein, wherein the substrate to be converted into another compound comprises one, two or more double bonds, preferably comprises two or more double bonds. A further preferred embodiment of the present invention is a use as defined herein, wherein the substrate to be isomerized and/or converted into another compound further comprises one or more heteroatom(s), preferably further comprises one or more nitrogen atom(s).

Furthermore, a preferred embodiment of the present invention is a use as defined herein, wherein the substrate to be isomerized is selected from the group consisting of N,N- dimethylgeranylamine, / , /V-diethylgeranylamine, 1 -[3,7-dimethylocta-2,6- dienyl]pyrrolidine, 4-[3,7-dimethylocta-2,6-dienyl]morpholine, /V,/V-diphenylgeranylamine, /V,/V-diethyl-3-methylbut-2-en-1 -amine, /V,/V-diethyl-3-methylhept-2-en-1 -amine, /V,/V- diethylhex-2-en-1 -amine, 3-cyclohexyl-/V,/V-diethylprop-2-en-1 -amine, /V,/V-diethyl-4,4,4- trifluorobut-2-en-1 -amine, /V,/V-diethyl-2-methylbut-2-en-1 -amine, /V,/V-diethyl-prop-2-en-1- amine, /V,/V-diethyl-but-3-en-1 -amine, /V,/V-diethyl-pent-4-en-1 -amine, A/-[(cyclohex-1-en-

1-yl)methyl]-/V-ethylethanamine, /V,/V-diethyl-3-phenylprop-2-en-1 -amine, 3-(4- chlorophenyl)-/V,/V-diethylprop-2-en-1 -amine, 3-(4-trifluoromethylphenyl)-A/,A/-diethylprop-

2-en-1 -amine, 3-(4-methoxyphenyl)-A/,A/-diethylprop-2-en-1 -amine, 3-(4-te/Y-butylphenyl)- /V,/V-diethylprop-2-en-1 -amine, 3-(4-cyanophenyl)-/V,/V-diethylprop-2-en-1 -amine, /V, N- diethyl-3-phenylbut-2-en-1 -amine, /V,/V-diethyl-3-(4-fluorophenyl)-3-phenylprop-2-en-1- amine, /V,/V-diethyl-3-(1 ,3,5-trimethylphenyl)-3-phenylprop-2-en-1-amine, and (2E,2’E)- 3,3’-(1 ,4-phenylene)bis(N,N-diethylprop-2-en-1 -amine), preferably wherein the substrate to be isomerized is /V, /V-diethylgeranylamine.

The use as defined herein is particularly advantageous for the isomerization of the substrates as defined herein.

According to a ninth aspect of the present invention, the stated object is achieved by a process, preferably hydrogen transfer reaction, more preferably for the (regio- )isomerization of a double bond in a substrate and/or for the conversion of a substrate into another compound, comprising or consisting of the following steps: a) Providing a coordination complex as defined herein or a coordination complex obtained or obtainable according to a process as defined herein, b) providing a substrate, preferably to be isomerized and/or to be converted into another compound, preferably wherein the substrate comprises one, two or more double bonds, c) contacting the coordination complex provided in step a) with the substrate provided in step b), and d) carrying out a catalytic reaction, preferably a (regio-)isomerization reaction, on the substrate catalyzed by the coordination complex.

Preferably, the substrate provided in step b) comprises two or more double bonds.

More preferably, the substrate provided in step b) comprises two or more double bonds and by applying the steps of the process according to the invention only one of the double bonds in the substrate is selectively (regio-)isomerized while the position of the other double bond(s) remains unchanged.

Preferably, the solvent (if present) used in the process as defined herein, more preferably used in step d) of the process, is selected from the group consisting of tetrahydrofuran, 2- methyltetrahydrofuran, toluene, cyclohexane, benzene, xylene, dibutyl ether, dioxane, hexane, and heptane.

Preferably, carrying out the catalytic reaction in step d) takes place under homogenous catalysis.

Another preferred embodiment according to the present invention is a process as defined herein, wherein the substrate provided in step b) comprises one or more heteroatom(s), preferably comprises one or more nitrogen atom(s), most preferably wherein the substrate provided in step b) is selected from the group consisting of N, /V-dimethylgeranylamine N, N- diethylgeranylamine, 1-[3,7-dimethylocta-2,6-dienyl]pyrrolidine, 4-[3,7-dimethylocta-2,6- dienyl]morpholine, N, /V-diphenylgeranylamine, /V,/V-diethyl-3-methylbut-2-en-1 -amine, /V,/V-diethyl-3-methylhept-2-en-1 -amine, /V,/V-diethylhex-2-en-1 -amine, 3-cyclohexyl-/V,/V- diethylprop-2-en-1 -amine, /V,/V-diethyl-4,4,4-trifluorobut-2-en-1 -amine, A/,/V-diethyl-2- methylbut-2-en-1 -amine, /V,/V-diethyl-prop-2-en-1 -amine, /V,/V-diethyl-but-3-en-1 -amine, /V,/V-diethyl-pent-4-en-1 -amine, /V-[(cyclohex-1-en-1-yl)methyl]-/V-ethylethanamine, A/,/V- diethyl-3-phenylprop-2-en-1 -amine, 3-(4-chlorophenyl)-/V,/V-diethylprop-2-en-1 -amine, 3- (4-trifluoromethylphenyl)-A/,A/-diethylprop-2-en-1 -amine, 3-(4-methoxyphenyl)-A/,A/- diethylprop-2-en-1 -amine, 3-(4-te/Y-butylphenyl)-/V,/V-diethylprop-2-en-1 -amine, 3-(4- cyanophenyl)-/V,/V-diethylprop-2-en-1 -amine, /V,/V-diethyl-3-phenylbut-2-en-1 -amine, /V,/V- diethyl-3-(4-fluorophenyl)-3-phenylprop-2-en-1 -amine, N, A/-d iethy l-3-(1 ,3,5- trimethylphenyl)-3-phenylprop-2-en-1 -amine, and (2E,2’E)-3,3’-(1 ,4-phenylene)bis(N,N- diethylprop-2-en-1 -amine). Most preferably, the substrate provided in step b) is /V,/V-diethylgeranylamine.

Advantageously, the coordination complexes according to the present invention can be used for the selective (regio-)isomerization of one of the double bonds of N,N- diethylgeranylamine and/or for its conversion into another compound such as e.g. into citronellal.

According to another aspect of the present invention, the stated object is achieved by a coordination complex obtained or obtainable by a process comprising or consisting of the following steps: a) Providing a precursor coordination complex, wherein the coordination centre of the precursor coordination complex is a rhodium, ruthenium, palladium, iridium, manganese, iron, cobalt, or nickel atom or is a rhodium, ruthenium, palladium, iridium, manganese, iron, cobalt, or nickel ion or is a 3d transition metal atom or ion, and/or preferably wherein one or two or three or more or all of the ligands of the precursor coordination complex is/are (a) bidentate ligand(s), b) providing a compound of formula (IV)

(IV), wherein R¹ is a residue independently selected from, preferably wherein R¹ is a residue selected from, the group consisting of

or R¹ is a residue according to formula (II) wherein R³, R⁴, and R⁵ are independently selected from the group consisting of H, alkyl, or aryl, and/or R³ forms an aromatic ring with R⁴ and/or R⁴ forms an aromatic ring with R⁵,

and wherein R² is a residue selected from the group consisting of or R² is a residue according to formula (II) wherein R³, R⁴, and R⁵ are independently selected from the group consisting of H, alkyl, or aryl, and/or R³ forms an aromatic ring with R⁴ and/or R⁴ forms an aromatic ring with R⁵, and preferably wherein in case R¹ is , R² is not or vice versa, and/or then the coordination centre of the precursor coordination complex provided in step a) is not a rhodium atom or ion, and/or in case both of R¹ and R² are then the coordination centre of the precursor coordination complex provided in step a) is not a rhodium atom or ion, and/or in case both of R¹ and R² are then the coordination centre of the precursor coordination complex provided in step a) is not a ruthenium atom or ion, and/or in case both of R¹ and R² are then the coordination centre of the precursor coordination complex provided in step a) is not a palladium atom or ion, and/or in case both of R¹ and R² are then the coordination centre of the precursor coordination complex provided in step a) is not a cobalt atom or ion, and/or in case both of R¹ and R² are then the coordination centre of the precursor coordination complex provided in step a) is not a nickel atom or ion, and/or in case both of R¹ and R² are then the coordination centre of the precursor coordination complex provided in step a) is not an iron atom or ion, and/or in case both of R¹ and R² are then the coordination centre of the precursor coordination complex provided in step a) is not an atom or ion selected from the group consisting of rhodium, palladium, cobalt, nickel, and iron, c) producing a solution or suspension comprising the precursor coordination complex provided in step a), the compound of formula (IV) provided in step b), and one or more solvent(s), preferably one or more non-polar solvent(s), more preferably wherein the one or more solvents) is/are selected from the group consisting of tetrahydrofuran, 2-methyltetrahydrofuran, toluene, cyclohexane, benzene, xylene, dibutyl ether, dioxane, hexane, and heptane, d) adding, preferably dropwise or portionwise, one or more reducing agent(s) to the solution or suspension produced in step c), preferably wherein the one or more reducing agent(s) is/are selected from the group consisting of diisobutylaluminium hydride, triethylaluminium, diisobutylaluminium hydride-tetrahydrofuran-solution, diisobutylaluminium hydride-toluene-solution, aluminium hydride, N,N- dimethylethylamine complex, lithium diisobutyl-tert-butoxyaluminium hydride, lithium aluminium hydride, sodium borohydride, and sodium triethylborohydride, e) optionally, isolating the coordination complex formed in step d) from the reaction mixture.

According to a preferred embodiment of the compound of formula (IV) as defined herein, R¹ and R² are the same. According to another preferred embodiment of the compound of formula (IV) as defined herein, R¹ and R² are different from one another. According to another preferred embodiment of the compound of formula (IV) as defined herein, both R¹ residues are the same.

Preferably, the precursor coordination complex provided in step a) and the compound of formula (IV) provided in step b) are mixed together in solid form, preferably under an inert gas, more preferably an argon, atmosphere, before the one or more solvents) (as defined herein) are added in step c) of the process as defined herein. A preferred embodiment according to the present invention is a coordination complex obtained or obtainable by a process as defined herein, wherein the compound of formula (IV) provided in step b) is selected from the group consisting of

L29 According to another preferred embodiment according to the present invention, both one or more compounds of formula (I) as defined herein (cf. further above) and one or more compounds of formula (IV) as defined herein are provided in step b) of the process as defined herein.

According to another aspect of the present invention, the stated object is achieved by a process comprising or consisting of the following steps: a) Providing a precursor coordination complex, wherein the coordination centre of the precursor coordination complex is a rhodium, ruthenium, palladium, iridium, manganese, iron, cobalt, or nickel atom or is a rhodium, ruthenium, palladium, iridium, manganese, iron, cobalt, or nickel ion or is a 3d transition metal atom or ion, and/or preferably wherein one or two or three or more or all of the ligands of the precursor coordination complex is/are (a) bidentate ligand(s), b) providing a compound of formula (IV)

(IV), wherein R¹ is a residue independently selected from, preferably wherein R¹ is a residue selected from, the group consisting of or R¹ is a residue according to formula (II) wherein R³, R⁴, and R⁵ are independently selected from the group consisting of H, alkyl, or aryl, and/or R³ forms an aromatic ring with R⁴ and/or R⁴ forms an aromatic ring with R⁵, and wherein R² is a residue selected from the group consisting of or R² is a residue according to formula (II) wherein R³, R⁴, and R⁵ are independently selected from the group consisting of H, alkyl, or aryl, and/or R³ forms an aromatic ring with R⁴ and/or R⁴ forms an aromatic ring with R⁵, and preferably wherein in case R¹ is , R² is not or vice versa, and/or then the coordination centre of the precursor coordination complex provided in step a) is not a rhodium atom or ion, and/or in case both of R¹ and R² are then the coordination centre of the precursor coordination complex provided in step a) is not a rhodium atom or ion, and/or in case both of R¹ and R² are then the coordination centre of the precursor coordination complex provided in step a) is not a ruthenium atom or ion, and/or in case both of R¹ and R² are then the coordination centre of the precursor coordination complex provided in step a) is not a palladium atom or ion, and/or in case both of R¹ and R² are then the coordination centre of the precursor coordination complex provided in step a) is not a cobalt atom or ion, and/or in case both of R¹ and R² are then the coordination centre of the precursor coordination complex provided in step a) is not a nickel atom or ion, and/or in case both of R¹ and R² are then the coordination centre of the precursor coordination complex provided in step a) is not an iron atom or ion, and/or in case both of R¹ and R² are then the coordination centre of the precursor coordination complex provided in step a) is not an atom or ion selected from the group consisting of rhodium, palladium, cobalt, nickel, and iron, c) producing a solution or suspension comprising the precursor coordination complex provided in step a), the compound of formula (IV) provided in step b), and one or more solvent(s), preferably one or more non-polar solvent(s), more preferably wherein the one or more solvents) is/are selected from the group consisting of tetra hydrofuran, 2-methyltetrahydrofuran, toluene, cyclohexane, benzene, xylene, dibutyl ether, dioxane, hexane, and heptane, d) adding, preferably dropwise or portionwise, one or more reducing agent(s) to the solution or suspension produced in step c), preferably wherein the one or more reducing agent(s) is/are selected from the group consisting of diisobutylaluminium hydride, triethylaluminium, diisobutylaluminium hydride-tetrahydrofuran-solution, diisobutylaluminium hydride-toluene-solution, aluminium hydride, N,N- dimethylethylamine complex, lithium diisobutyl-tert-butoxyaluminium hydride, lithium aluminium hydride, sodium borohydride, and sodium triethylborohydride, e) optionally, isolating the coordination complex formed in step d) from the reaction mixture.

According to another preferred embodiment according to the present invention, both one or more compounds of formula (I) as defined herein (cf. further above) and one or more compounds of formula (IV) as defined herein are provided in step b) of the process according to the invention.

(Preferred) embodiments of the coordination complexes according to the invention correspond to or can be derived from the (preferred) embodiments of the processes according to the invention which are explained above or vice versa. (Preferred) embodiments of the coordination complexes and the processes according to the invention correspond to or can be derived from the (preferred) embodiments of the uses according to the invention which are explained above or vice versa. Moreover, what has been stated herein for the compounds of formula (I) applies accordingly to the compounds of formula (IV) and vice versa and what has been stated herein for one production process according to the invention applies accordingly to the other production processes according to the invention. Lastly, the (preferred) embodiments described herein can be arbitrarily combined with each other as long as technically sensible.

The invention will now be described in more detail hereinafter with references to the examples. Further aspects of the present invention are disclosed in the accompanying claims.

Description of Figures:

Figure 1 shows the crystal structure of tris(benzo[1 ,2-b:4,5-b']difuran-2-yl)phosphine.

Crystal data of Figure 1 : C30H15O6P, M = 502.39, monoclinic, space group P2i/c, a = 22.3733(7), b = 6.3225(1), c = 16.7540(5) A, b = 110.705(2)°, V = 2216.87(11) A³, T = 150(2) K, Z = 4, 35378 reflections measured, 6000 independent reflections (Rnt = 0.0226), final R values (/ > 2o(/)): R1 = 0.0383, WR2 = 0.1059, final R values (all data): R1 = 0.0422, WR2 = 0.1090, 334 parameters.

Figure 2 shows the crystal structure of di(benzofuran-2-yl)(dibenzo[b,d]furan-4-yl) phosphine.

Crystal data of Figure 2: C28H17O3P, M = 432.38, monoclinic, space group P2i, a = 6.4528(3), b = 14.4005(5), c= 11 .2976(5) A, p = 103.265(3)°, V= 1021 .80(8) A³, T= 150(2) K, Z = 2, 15678 reflections measured, 5523 independent reflections (Rint = 0.0156), final R values (/ > 2o(/)): R1 = 0.0301 , WR2 = 0.0788, final R values (all data): R1 = 0.0314, WR2 = 0.0795, 289 parameters.

Figure 3 shows the crystal structure of tri(benzofuran-2-yl)phosphine.

Crystal data of Figure 3: C24H15O3P, M = 382.33, monoclinic, space group P2i, a = 5.9038(7), b = 16.1922(18), c = 9.7412(11) A, p = 97.5899(19)°, V = 923.06(18) A³, T = 150(2) K, Z = 2, 13574 reflections measured, 4465 independent reflections (Rint = 0.0193), final R values (/ > 2o(/)): R1 = 0.0511 , WR2 = 0.1332, final R values (all data): R1 = 0.0546, WR2 = 0.1370, 242 parameters.

Figure 4 shows the crystal structure of the solid obtained from experiment II. III. I of the mechanistic investigations of the catalytic cycle. Crystal data of Figure 4: C66H60C0O12P2, M = 1166.01 , triclinic, space group Pl, a = 9.6953(9), b = 10.0691 (10), c= 16.4128(15) A, a = 87.055(3), p = 75.572(2), y= 67.290(2)°, V = 1429.6(2) A³, T = 150(2) K, Z = 1 , 72188 reflections measured, 6913 independent reflections (Rint = 0.0438), final R values (/ > 2o(/)): R1 = 0.0391 , WR2 = 0.1066, final R values (all data): R1 = 0.0454, WR2 = 0.1129, 369 parameters.

Figure 5 shows the crystal structure of the solid obtained from experiment II. III. II of the mechanistic investigations of the catalytic cycle.

Crystal data of Figure 5: C96H60C0O12P4, M = 1588.25, trigonal, space group R3, a = 22.9793(6), c = 17.0108(5) A, V = 7779.1 (5) A³, T = 150(2) K, Z = 3, 45475 reflections measured, 6095 independent reflections (Rint = 0.046), final R values (/ > 2o(/)): R1 = 0.0355, WR2 = 0.0886, final R values (all data): R1 = 0.0371 , WR2 = 0.0897, 340 parameters.

Examples:

I. Synthesis and characterization of the compounds of formula (I) and (IV)

In the following, the manufacturing procedures for the synthesis of the compounds of formula (I) and (IV) according to the invention will be presented. Furthermore, the obtained X-Ray structures will be shown. Diffraction data was collected on a Bruker Kappa APEX II Duo and an IPDS II diffractometer, respectively. The structures were solved by intrinsic phasing (SHELXT: Sheldrick, G. M. Acta Cryst. 2015, A71, 3.) and refined by full-matrix least-squares procedures on F² (SHELXL-2019: Sheldrick, G. M. Acta Cryst. 2015, C71, 3.). XP (Bruker AXS) was used for graphical representations. Contributions of disordered solvent in complex [Co(PR3)4] shown in Figure 5 were removed from the diffraction data using the SQUEEZE procedure in PLATON (Spek, A. L. Acta Cryst. 2015, C71, 9). If not explicitly differently labelled, the atoms in the crystal structures correspond to carbon atoms. 1.1 Synthesis of tris(4,5-dimethylfuran-2-yl)phosphine

Under argon atmosphere, 2,3-dimethylfuran (787 mg, 8.19 mmol, 3 eq.) was weighted in a flame dried Schlenk flask. Then, 20 mL anhydrous diethyl ether was added, and the solution was cooled to -78°C. Under stirring, n-Buli (2.5 M, 3.3 mL, 8.19 mmol, 3 eq.) was slowly added with a syringe and the temperature was kept for 1 h at -78 °C. Afterwards, the reaction mixture was allowed to warm up to room temperature and stirred for 2 h. Then, the lithiated dimethylfuran solution was cooled again to -78 °C and phosphorus trichloride (375 mg, 2.73 mmol, 1 eq.) was slowly added with a syringe. The solution was warmed up to room temperature and stirred overnight. To remove the lithium chloride, the orange/brown suspension was filtrated with a syringe filter. Next, the solvent was removed in vacuo, which yielded an orange oil. Finally, a colourless oil (1.41 g, 5.58 mmol, q (yield): 82%) was obtained by high vacuum distillation.

1 H-NMR (400 MHz, THF) 6 = 6.44 (dt, J=0.9, 0.4, 3H), 2.17 (s, 9H), 1 .88 (s, 9H).

13C-NMR (101 MHz, THF) 6 = 152.83 (d, J=3.4), 147.49 (d, J=3.5), 124.15 (d, J=19.3), 115.93 (d, J=5.0), 1 1.39, 9.52.

³¹P-NMR (162 MHz, THF) 6 = -76.01 .

HRMS (ESI): m/z calcd. for C18H21O3P: 317.1306 [M+H]⁺, found: 317.1306. l.ll Synthesis of bis(furan-2-yl)(isobutyl)phosphine Under argon atmosphere, bis(2-furyl)-phosphine chloride (0.55 g, 2.74 mmol, 1 eq.) was weighted in a flame dried Schlenk flask. Then, 15 mL anhydrous diethyl ether were added and the solution was cooled to -78 °C. Isobutyllithium (1.7 M, 1.61 mL, 2.74 mmol, 1 eq.) was slowly transferred to the stirring solution and the temperature was kept at -78 °C for 1 h. The reaction mixture was allowed to warm up to room temperature and stirred overnight. Afterwards, the lithium chloride was removed from the reaction mixture by anaerobic filtration with a syringe filter, the solvent was removed in vacuo. Finally, the received yellow oil was purified by vacuum distillation, which yielded the target product as a colourless oil (0.49 g, 2.21 mmol, q: 81 %).

¹H-NMR (400 MHz, THF) 6 = 7.66 (dd, J = 1 .9, 0.8, 2H), 6.85 - 6.54 (m, 2H), 6.53 - 6.13 (m, 2H), 2.09 (d, J = 7.0, 2H), 1.61 (ddp, J = 13.5, 9.5, 6.7, 1 H), 0.97 (d, J = 6.7, 6H).

¹³C-NMR (101 MHz, THF) 6 = 153.01 (d, J=17.0), 147.52 (d, J=1 .8), 120.13 (d, J=24.2), 111 .00 (d, J=5.5), 35.89 (d, J=2.6), 26.84 (d, J=14.4), 23.93 (d, J=9.9).

³¹P-NMR (162 MHz, THF) 6 = -64.88.

HRMS (ESI): m/z calcd. for C12H15O2P: 223.0888 [M+H]⁺, found: 223.0884.

1.111 Synthesis of ethoxydi(furan-2-yl)phosphine

A flame dried Schlenk flask was charged with sodium ethoxide (0.39 g, 5.76 mmol, 1.05 eq.) and 10 mL anhydrous THF. In another Schlenk flask, bis(2-furyl)-phosphine chloride (1.10 g, 5.48 mmol, 1 eq.) was dissolved in 10 ml anhydrous THF. At -20 °C, the sodium ethoxide solution was added dropwise to the bis(2-furyl)-phosphine chloride solution and the resulting reaction mixture was then allowed to stir at same temperature for 1 h. After the solution was warmed up to room temperature, the solvent was removed in vacuo. Finally, the obtained oil was purified by vacuum distillation, which yielded the target product as a colourless oil (0.75 g, 3.56 mmol, q: 65%). ¹H-NMR (400 MHz, THF) 6 = 7.78 (dd, J=1 .7, 0.7, 2H), 6.92 - 6.78 (m, 2H), 6.47 (dt, J=3.2, 1 .6, 2H), 3.79 - 3.72 (m, 2H), 1 .08 - 1 .04 (m, 3H).

¹³C-NMR (101 MHz, THF) 6 = 155.44 (d, J=23.4), 148.20 (d, J=3.4), 121.75 (d, J=23.3), 111 .01 (d, J=4.9), 65.31 , 16.84 (d, J=5.0).

³¹P-NMR (162 MHz, THF) 6 = 55.63.

HRMS (ESI): m/z calcd. for C10H11O3P: 211.0519 [M+H]⁺, found: 21 1.0522.

I. IV Synthesis of benzofuran-2-yl-di(furan-2-yl)phosphine

A flame dried Schlenk flask was charged with benzofuran (0.99 g, 8.42 mmol, 1 eq.) and 10 mL anhydrous diethyl ether. At -20 °C, n-BuLi (2.5 M, 3.37 mL, 8.42 mmol, 1 eq.) was added dropwise to the solution and the temperature was kept for 1 h. Then, the reaction mixture was allowed to slowly warm up to room temperature and stirred for 2 h. Bis(2-furyl)- phosphine chloride (1.69 g, 8.42 mmol, 1 eq.) was weighted in a separate Schlenk flask and was dissolved in 15 mL anhydrous diethyl ether. The lithiated benzofuran solution was transferred into a Schlenk dropping funnel and the orange solution was slowly added to the phosphine chloride at -78 °C. After complete addition of the benzofuran solution, the reaction mixture was warmed up to room temperature. Next, the lithium chloride was removed from the reaction mixture by anaerobic filtration with a syringe filter and the solvent was removed in vacuo. Then, a vacuum distillation of the crude oil was performed, yielding a colourless oil (1 .86 g, 6.59 mmol, q: 78%) as the desired product. The received oil started crystallising after the distillation was finished.

¹H-NMR (400 MHz, THF) 6 = 7.76 (dt, J = 1 .9, 0.9, 2H), 7.57 - 7.51 (m, 1 H), 7.45 (dd, J = 8.3, 1.0, 1 H), 7.26 (ddd, J = 8.3, 7.2, 1.4, 1 H), 7.17 (td, J = 7.5, 1.1 , 1 H), 7.00 (t, J = 1.1 , 1 H), 6.93 - 6.88 (m, 2H), 6.47 (dt, J = 3.4, 1 .7, 2H). ¹³C-NMR (101 MHz, THF) 6 = 158.70 (d, J=3.9), 154.15, 148.84 (d, J=2.5), 148.73 (d, J=2.8), 128.87 (d, J=4.6), 125.67, 123.42, 122.46 (d, J=24.2), 121.78, 116.79 (d, J=18.0), 111 .85, 111.48 (d, J=6.2).

³¹P-NMR (122 MHz, THF) 6 = -73.92.

HRMS (ESI): m/z calcd. for C16H11O3P: 305.0338 [M+Na]⁺, found: 305.0335.

I.V Synthesis of tri(benzofuran-3-yl)phosphine

Under argon atmosphere, 3-bromobenzofuran (450 mg, 2.28 mmol, 3 eq.) was weighted in a flame dried Schlenk flask. Then, 12 mL anhydrous diethyl ether were added, and the solution was cooled to -78 °C. Next, n-BuLi (2.5 M, 1 ml, 2.50 mmol, 3.3 eq.) was added dropwise to the solution, which resulted in a fast colour change to yellow. After stirring the solution for 1 h at -78 °C, phosphorus trichloride (104 mg, 0.76 mmol, 1 eq.) was added slowly. The reaction mixture was allowed to warm up to room temperature and stirred overnight. A light-yellow solution was obtained after the suspension was filtrated. The solvent was removed in vacuo, whereby a yellow solid was obtained. The desired product was isolated by column chromatography using n-hexane and 1 % ethyl acetate as eluents. After the solvent was removed in vacuo, a light-yellow solid was obtained (226 mg, 0.59 mmol, q: 78%). The phosphine was stored under argon.

¹H-NMR (400 MHz, THF) 6 = 7.70 (d, J=1 .5, 1 H), 7.59 - 7.54 (m, 1 H), 7.52 (dq, J=8.3, 1.1 , 1 H), 7.29 (ddd, J=8.3, 7.2, 1.3, 1 H), 7.19 - 7.13 (m, 1 H).

¹³C-NMR (101 MHz, THF) 6 = 156.30 (d, J=5.4), 149.51 (d, J=19.0), 128.88 (d, J=15.3), 124.67, 122.88, 120.84 (d, J=2.6), 111.36, 111.28.

³¹P-NMR (122 MHz, THF) 6 = -86.33.

HRMS (ESI): m/z calcd. for C24H15O3P: 383.0837 [M+H]⁺, found: 383.0828. I. VI Synthesis of tn(benzofuran-5-yl)phosphine

First, 5-bromobenzofuran (520 mg, 2.64 mmol, 3 eq.) was dissolved in 15 mL of anhydrous diethyl ether in a flame dried Schlenk flask. At -78 °C, t-BuLi (2.73 mmol, 3.1 eq.) was added slowly to the solution and the reaction mixture was kept for 1 h at this temperature. Then, phosphorus trichloride (121 mg, 0.88 mmol, 1 eq.) was added dropwise to the lithiated benzofuran compound at -78 °C. After warming up to room temperature, the white suspension was filtrated with a syringe filter to remove the lithium chloride, yielding a colourless solution. Next, the solvent was removed under reduced pressure and a white solid was received. Crystallization of the target phosphine was achieved by a concentrated dichloromethane (DCM) solution yielding colourless platelets. Finally, the obtained crystals were dried under reduced pressure overnight (180 mg, 0.47 mmol, q: 53%).

¹H-NMR (400 MHz, THF) 6 = 7.74 (d, J = 2.2, 1 H), 7.53 (dd, J = 7.3, 1 .7, 1 H), 7.51 - 7.45 (m, 1 H), 7.33 - 7.24 (m, 1 H), 6.76 (dd, J = 2.3, 1 .0, 1 H).

¹³C-NMR (101 MHz, THF) 6 = 156.21 , 146.51 , 133.10 (d, J=11 .7), 130.55 (d, J=24.1), 128.96 (d, J=8.1), 127.51 (d, J=20.6), 11 1.96 (d, J=8.4), 107.19.

³¹P-NMR (122 MHz, THF) 6 = -3.79.

HRMS (ESI): m/z calcd. for C24H15O3P: 383.0837 [M+H]⁺, found: 383.0836.

I .VI I Synthesis of tri(benzofuran-7-yl)phosphine First, 7-bromobenzofuran (1 .00 g, 5.07 mmol, 3 eq.) was weighted in a flame dried Schlenk flask. Then, 10 mL anhydrous diethyl ether were added and the solution was cooled to -78 °C, followed by the slow addition of n-BuLi (5.07 mmol, 3 eq.). After the reaction mixture stirred for approximately 2 h at -78 °C, phosphorus trichloride (0.23 g, 1.69 mmol, 1 eq.) was transferred dropwise to the lithiated benzofuran compound. The solution was allowed to slowly warm up to room temperature. Next, the suspension was filtrated with a syringe filter and a colourless solution was obtained. Then, the solvent was removed under vacuum, yielding a white solid. Finally, crystals of the target product (401 mg, 1 .05 mmol, q: 62%) were obtained from a concentrated dichloromethane phosphine solution at -30 °C.

¹H-NMR (400 MHz, THF) 6 = 7.67 (d, J=2.2, 3H), 7.61 (dd, J=7.7, 1.2, 3H), 7.08 (ddd, J=7.8, 7.4, 0.5, 3H), 6.83 (t, J=2.2, 3H), 6.80 - 6.74 (m, 3H).

¹³C-NMR (101 MHz, THF) 6 = 157.98 (d, J=17.6), 146.17, 129.64 (d, J=3.6), 127.93 (d, J=2.8), 123.70 (d, J=1 .5), 122.83, 118.52 (d, J=16.9), 106.96 (d, J=1 .8).

³¹P-NMR (162 MHz, THF) 6 = -44.82.

HRMS (ESI): m/z calcd. for C24H15O3P: 405.0651 [M+Na]⁺, found: 405.0649.

I .VI 11 Synthesis of tris(3-methylbenzofuran-2-yl)phosphine

Under argon atmosphere, 3-methylbenzofuran (1.05 g, 7.91 mmol, 3.1 eq.) was dissolved in 20 mL of anhydrous diethyl ether. Then, n-BuLi (2.5 mM, 3.16 mL, 7.91 mmol, 3.1 eq.) was added slowly to the solution at -78 °C. The reaction mixture was kept at -78 °C for 1 h, before the solution was warmed up to room temperature. The solution stirred 2 h at room temperature. At -78 °C, phosphorus trichloride (0.35 g, 2.55 mmol, 1 eq.) was added dropwise to the lithiated benzofuran compound. After that, the solution was allowed to slowly warm up to room temperature and a white suspension was obtained, which was filtrated with a syringe filter to remove the lithium chloride. The solvent was removed in vacuo and a white solid was obtained. Finally, the desired phosphine was obtained after column chromatography was performed using n-hexane and 0.5% ethyl acetate (0.93 g, 2.19 mmol, q: 86%).

¹H-NMR (400 MHz, THF) 6 = 7.57 - 7.50 (m, 3H), 7.45 (dt, J=8.2, 0.9, 3H), 7.28 (ddd, J=8.3, 7.1 , 1.4, 3H), 7.19 (td, J=7.4, 1 .0, 3H), 2.38 (s, 9H).

¹³C-NMR (101 MHz, THF) 6 = 158.08 (d, J=2.6), 146.54 (d, J=9.9), 130.09 (d, J=6.2), 127.58 (d, J=28.6), 126.16, 122.96, 120.29 (d, J=1 .8), 1 12.00, 8.95 (d, J=9.9).

³¹P-NMR (122 MHz, THF) 6 = -88.93.

HRMS (ESI): m/z calcd. for C27H21O3P: 447.1120 [M+Na]⁺, found: 447.1 119.

I. IX Synthesis of tris(benzo[1 ,2-b:4,5-b'1difuran-2-yl)phosphine

First, benzo[1 ,2-b:4,5-b']difuran (433 mg, 2.74 mmol, 3 eq.) was dissolved in 15 mL anhydrous diethyl ether in a Schlenk flask. Then, the solution was cooled to -78 °C and n- BuLi (2.5 M, 1 .1 mL, 2.75 mmol, 3 eq.) was added dropwise with a Schlenk dropping funnel. After the complete addition of n-BuLi, the reaction mixture was slowly warmed up to room temperature and stirred for 2 h. The yellow solution was cooled again to -78 °C and phosphorus trichloride (125 mg, 0.91 mmol, 1 eq.) was transferred dropwise to the reaction mixture. Then the solution was allowed to warm up to room temperature. As the next step, the light-yellow suspension was filtrated with a syringe filter to remove the lithium chloride. The solvent of the received yellow solution was removed in vacuo. Finally, the desired product was obtained after column chromatography was performed using n-hexane and 5% ethyl acetate (211 mg, 0.42 mmol, q: 46%). ¹H-NMR (400 MHz, THF) 6 = 7.78 (d, J=2.3, 3H), 7.72 - 7.66 (m, 6H), 7.42 - 7.36 (m, 3H), 6.89 (dd, J=2.2, 1.0, 3H).

¹³C-NMR (101 MHz, THF) 6 = 155.99 (d, J=4.4), 153.02, 152.57 (d, J=3.6), 147.57, 127.85, 126.77 (d, J=5.4), 119.16, 118.96, 107.40, 102.75 (d, J=1 .8).

³¹P-NMR (122 MHz, THF) 6 = -65.79.

HRMS (ESI): m/z calcd. for C30H15O6P: 503.0685 [M+H]⁺, found: 503.0684.

I.X Synthesis of di(benzofuran-2-yl)(methyl)phosphine

Under argon atmosphere, di(benzofuran-2-yl)chlorophosphine (601 mg, 2 mmol, 1 eq.) was charged in a 100 mL Schlenk flask. Then, 25 mL of anhydrous diethyl ether were added and the solution was cooled to -78 °C. A methyllithium solution (1 .6 M, 1 .25 mL, 2 mmol, 1 eq.) was injected dropwise under stirring and the solution was allowed to stir for 1 h at -78 °C. The reaction mixture was slowly warmed up to room temperature and stirred overnight. After the suspension was anaerobically filtrated with a syringe filter, a light-yellow solution was obtained. Next, the solvent was removed in vacuo. The obtained yellow solid was recrystallized in dichloromethane, yielding colourless crystals (398 mg, 1 .42 mmol, q: 71 %).

¹H-NMR (400 MHz, THF) 6 = 7.55 (ddd, J=7.7, 1 .4, 0.8, 2H), 7.45 (dq, J=8.3, 1 .0, 2H), 7.28 - 7.21 (m, 2H), 7.20 - 7.16 (m, 2H), 7.15 (dd, J=1 .7, 1 .0, 2H), 1 .82 (d, J=4.1 , 3H).

¹³C-NMR (101 MHz, THF) 6 = 158.63 (d, J=2.1), 156.59 (d, J=19.3), 128.97 (d, J=5.5), 125.62, 123.40, 121.74, 116.04 (d, J=21.9), 111.79, 8.31 (d, J=5.5).

³¹P-NMR (162 MHz, THF) 6 = -63.12.

HRMS (ESI): m/z calcd. for C17H13O2P: 281 .0731 [M+H]⁺, found 281 .0726. I .XI Synthesis of di(benzofuran-2-yl)(phenyl)phosphine

The synthesis was carried out following the same procedure as described for di(benzofuran-2-yl)(methyl)phosphine above with phenyllithium (1.9 M, 1 .05 mL, 2 mmol, 1 eq.) instead of methyllithium. The desired product was obtained after column chromatography was performed using n-hexane and 5% ethyl acetate (322 mg, 0.94 mmol, q: 47%).

¹H-NMR (400 MHz, THF) 6 = 7.67 - 7.59 (m, 2H), 7.57 (ddd, J=7.7, 1 .4, 0.7, 2H), 7.48 (dq, J=8.3, 1.0, 2H), 7.41 - 7.35 (m, 3H), 7.32 - 7.24 (m, 2H), 7.23 - 7.15 (m, 2H), 7.11 (dd, J=1 .5, 1.0, 2H).

¹³C-NMR (75.49 MHz, THF) 6 = 159.02 (d, J=3.0), 154.79 (d, J=11 .1), 134.21 (d, J=21.0), 133.63 (d, J=2.9), 130.36, 129.35 (d, J=7.7), 128.83 (d, J=5.3), 125.91 , 123.54, 121.91 , 118.30 (d, J=20.2), 111.96.

³¹P-NMR (162 MHz, THF) 6 = -44.83.

Under argon atmosphere, di(benzofuran-2-yl)chlorophosphine (301 mg, 1 mmol, 1 eq.) was charged into a 100 mL Schlenk flask together with 15 mL of anhydrous THF and the solution was cooled to -78 °C. Then, another Schlenk flask was charged with degassed 2- bromoanisole (206 mg, 1.1 mmol, 1.1 eq.) and 10 mL anhydrous THF were added. At -78 °C, n-BuLi (2.5 M, 0.44 mL, 1.1 mmol, 1 eq.) was added dropwise to the 2-bromoanisole solution and the temperature was kept for 1 h. Then, the lithiated anisole compound was transferred dropwise to the phosphine chloride solution at -78 °C. The reaction mixture was slowly warmed up to room temperature and stirred overnight. After the solvent was removed in vacuo, a column chromatography was performed using n-hexane and 15% ethyl acetate, yielding a white solid (156 mg, 0.42 mmol, q: 42%).

¹H-NMR (400 MHz, THF-c/_s): 6 = 7.55 (ddd, J=7.7, 1.4, 0.7, 2H), 7.46 (dq, J=8.3, 0.9, 2H), 7.41 - 7.32 (m, 1 H), 7.30 - 7.22 (m, 2H), 7.21 - 7.15 (m, 2H), 7.14 - 7.08 (m, 1 H), 7.01 (q, J=1 .3, 2H), 7.00 - 6.96 (m, 1 H), 6.89 (tt, J=7.5, 0.9, 1 H), 3.76 (s, 3H).

¹³C-NMR (75.49 MHz, THF-c/_s): 6 = 162.16 (d, J=16.6), 158.93 (d, J=3.3), 155.13 (d, J=11 .3), 134.07, 131 .83, 129.05 (d, J=5.1), 125.57, 123.37, 122.01 (d, J=4.0), 121 .75, 121.71 , 117.83 (d, J=18.5), 111 .91 , 111 .33 (d, J=2.1), 55.83.

³¹P-NMR (162 MHz, THF-c/_s): 6 = -44.83.

HRMS (ESI): m/z calcd. for C23H17O3P: 373,0993 [M+H]⁺, found: 373.0992.

I.XIII Synthesis of di(benzofuran-2-yl)(furan-2-yl)phosphine

Degassed furan (142 mg, 2.1 mmol, 1.05 eq.) was charged into a 100 mL Schlenk flask together with 20 mL anhydrous diethyl ether. At -78 °C, n-BuLi (2.5 M, 0.8 mL, 2 mmol, 1 eq.) was added dropwise to the solution under stirring. The reaction mixture was allowed to slowly warm up to room temperature and stirred for 2 h. A separate Schlenk flask was charged with bis(benzofuran-2-yl)-phosphine chloride (601 g, 2 mmol, 1 eq.) and 15 ml anhydrous diethyl ether. The lithiated furan solution was transferred into a Schlenk dropping funnel and the solution was added dropwise to the phosphine chloride solution at -78 °C. After the reaction mixture was warmed up to room temperature and stirred for 2 h, the suspension was filtrated with a syringe filter. Then the solvent was removed in vacuo, which yielded a yellow oil. Finally, a colorless oil of the target product was received after vacuum distillation. (1 .86 g, 6.59 mmol, q: 78%).

¹H-NMR (400 MHz, THF) 6 = 7.83 (dt, J=1 .6, 0.7, 1 H), 7.57 (ddd, J=7.7, 1 .4, 0.7, 2H), 7.48 (dq, J=8.3, 0.9, 2H), 7.28 (ddd, J=8.4, 7.2, 1.4, 2H), 7.22 - 7.13 (m, 4H), 7.05 (ddd, J=3.3, 2.0, 0.7, 1 H), 6.52 (dt, J=3.4, 1.7, 1 H).

¹³C-NMR (101 MHz, THF) 6 = 158.85 (d, J=3.8), 152.98 (d, J=3.0), 149.23 (d, J=3.0), 128.82 (d, J=5.4), 125.96, 123.62, 123.55, 123.28, 121.95, 117.86 (d, J=19.9), 111.97, 11 1.68 (d, J=6.6).

³¹P-NMR (122 MHz, THF) 6 = -70.87.

HRMS (ESI): m/z calcd. for C20H13O3P: 355.0494 [M+Na]⁺, found: 355.0500.

I .X I V Synthesis of di(benzofuran-2-yl)(1 ,3-dioxolan-2-yl)phosphine

According to the procedure of Shiner et al., 2-lithio-1 ,3-dioxolan was prepared from (1 ,3- dioxolan-2-yl)tri-n-butylstannane (381 mg, 1 .05 mmol, 1 eq.) by the addition of n-BuLi (2.5 M, 0.42 mL, 1.05 mmol, 1 eq.) at -78 °C. A separate Schlenk flask was charged with bis(benzofuran-2-yl)-phosphine chloride (301 g, 1 mmol, 1 eq.) and 10 mL anhydrous THF. At -78 °C, the 2-lithio-1 ,3-dioxolan THF solution was added slowly to phosphine chloride solution and the temperature was kept for 1 h. Then the reaction mixture was allowed to warm up to room temperature and stirred overnight. After the solvent was removed in vacuo, the received yellow solid was dissolved in anhydrous dichloromethane. The obtained yellow solution was filtrated with a syringe filter to remove the lithium chloride. Finally, colorless crystals (115 mg, 0.34 mmol, q: 34%) were received from a concentrated DCM solution at -32 °C.

¹H-NMR (400 MHz, THF-c/_s): 6 = 7.58 (ddd, J=7.7, 1 .4, 0.7, 2H), 7.49 (dq, J=8.3, 0.9, 2H), 7.34 - 7.23 (m, 4H), 7.23 - 7.15 (m, 2H), 6.41 (d, J=8.6, 1 H), 4.14 - 3.86 (m, 4H). ¹³C-NMR (101 MHz, THF-c/₈): 6 = 158.68 (d, J=2.4), 153.06 (d, J=16.5), 128.78 (d, J=5.8), 125.87, 123.45, 121.86, 1 18.36 (d, J=19.5), 111.90, 106.94 (d, J=16.5), 66.02 (d, J=3.0).

³¹P-NMR (161.98 MHz, THF-c/_s): 6 = -62.86.

HRMS (ESI): m/z calcd. for C19H15O4P: 366.0600 [M+Na]⁺, found: 366.0608.

I .XV Synthesis of di(benzofuran-2-yl)(dibenzo[b,d1furan-4-yl)phosphine

A flame dried Schlenk flask was charged with dibenzofuran (353 mg, 2.1 mmol, 1 .05 eq.) and 10 mL anhydrous diethyl ether. At -20 °C, n-BuLi (2.5 M, 0.8 mL, 2 mmol, 1 eq.) was added dropwise to the solution and the temperature was kept for 1 h. Then the reaction mixture was allowed to slowly warm up to room temperature and stirred for 2 h. Bis(2-furyl)- phosphine chloride (601 mg, 2 mmol, 1 eq.) was weighted in a separate Schlenk flask and was dissolved in 15 mL of anhydrous diethyl ether. The lithiated benzofuran solution was transferred into a Schlenk dropping funnel and the orange solution was slowly added to the phosphine chloride at -78 °C. After the complete addition of the benzofuran solution, the reaction mixture was warmed up to room temperature. Next, the lithium chloride was removed from the reaction mixture by anaerobic filtration with a syringe filter and the solvent was removed in vacuo. Then, column chromatography was performed using n-hexane and 0.5% ethyl acetate, yielding a white solid (545 mg, 1.26 mmol, q: 63%) as the desired product.

¹H-NMR (400 MHz, THF) 6 = 8.10 (dd, J=7.7, 1.3, 1 H), 8.03 (ddd, J=7.7, 1.4, 0.7, 1 H), 7.57 (ddd, J=7.8, 1 .4, 0.7, 2H), 7.55 - 7.46 (m, 4H), 7.46 - 7.40 (m, 1 H), 7.40 - 7.25 (m, 4H), 7.24 - 7.14 (m, 4H).

¹³C-NMR (101 MHz, THF) 6 = 159.12 (d, J=3.5), 158.74 (d, J=17.9), 156.96, 153.39 (d, J=9.4), 132.37 (d, J=2.2), 128.89 (d, J=5.4), 128.22, 125.98, 125.00 (d, J=3.5), 124.51 (d, J=2.3), 124.05 (d, J=1 .8), 123.71 , 123.56, 123.06, 121 .98, 121 .45, 118.81 (d, J=20.6), 116.82 (d, J=8.4), 112.36, 1 12.02.

³¹P-NMR (162 MHz, THF) 6 = -58.49.

HRMS (ESI): m/z calcd. for C28H17O3P: 455.0807 [M+Na]⁺, found: 455.0808.

I .XVI Synthesis of ethyldi(furan-2-yl)phosphine

Dry and freshly activated magnesium powder (0.158 g, 6.5 mmol, 1 .3 equiv.) was added to a round bottom flask and the system was flamed under vacuum. After cooling down the system, Et2O (15 mL, 0.33 mol/L) was added under argon. To this stirring solution, ethylbromide (1.1 equiv., 5.5 mmol) was added dropwise. The reaction was stirred for 2h at room temperature, while it was possible to see consumption of powder magnesium and evolution of bubbles (if this is not visible, one can warm up the reactional mixture with hands or with slightly warm water). Then, it was cooled down to -78°C and chlorodi(furan-2- yl)phosphine(1 .028 g, 5 mmol, 1.0 equiv.) was added dropwise. The reaction was slowly warmed up to room temperature and it was stirred overnight. After this period, the reaction was filtered in a 22 pL filter under argon, the solvent was removed under vacuum, and distillation under vacuum afforded the desired product as a colorless oil (652.9 mg, 3.36 mmol; q = 67%).

¹H NMR (300 MHz, CDCb) 6 = 7.63 (dd, J = 1 .8, 0.8 Hz, 2H), 6.74 (ddd, J = 3.2, 1 .9, 0.8 Hz, 2H), 6.39 (dt, J = 3.2, 1 .6 Hz, 2H), 2.15 (q, J = 7.6, 2H), 1 .05 (dt, J = 18.4, 7.6 Hz, 3H).

¹³C NMR (75 MHz, CDCb) 6 = 151 ,8(d, J = 17.2 Hz), 146.9 (d, J = 1.4 Hz), 120.2(d, J = 24.2 Hz), 110.6(d, J = 6.0 Hz), 18.5, 10.11 (d, J = 15.9 Hz). ³¹P NMR (122 MHz, CDCb) 6 = -57.2.

HRMS (ESI+) m/z calculated for [C10H11O2PH+] = 195.0570, found 195.0575.

I .XVI I Synthesis of propyldi(furan-2-yl)phosphine

Dry and freshly activated magnesium powder (0.158 g, 6.5 mmol, 1 .3 equiv.) was added to a round bottom flask and the system was flamed under vacuum. After cooling down the system, Et2O (15 mL, 0.33 mol/L) was added under argon. To this stirring solution, n- propylbromide (1 .1 equiv., 5.5 mmol) was added dropwise. The reaction was stirred for 2h at room temperature, while it was possible to see consumption of powder magnesium and evolution of bubbles (if this is not visible, one can warm up the reactional mixture with hands or with slightly warm water). Then, it was cooled down to -78°C and chlorodi(furan-2- yl)phosphine(1 .028 g, 5 mmol, 1.0 equiv.) was added dropwise. The reaction was slowly warmed up to room temperature and it was stirred overnight. After this period, the reaction was filtered in a 22 pL filter under argon, the solvent was removed under vacuum, and distillation under vacuum afforded the desired product as a colorless oil (570.8mg, 2.74 mmol, q: 55%).

¹H NMR (300 MHz, CDCb) 6 7.62 (dd, J = 1 .8, 0.8 Hz, 2H), 6.73 (ddd, J = 3.3, 1 .9, 0.8 Hz, 2H), 6.38 (ddd, J = 3.3, 1.8, 1.5 Hz, 2H), 2.19 -2.10 (m, 2H), 1.51 -1.35 (m, 2H), 1.00 (t, J = 7.3 Hz, 3H).

¹³C NMR (75 MHz, CDCb) 6 152.0(d, J = 17.3 Hz), 146.9 (d, J = 1.5 Hz), 120.0 (d, J = 24.6 Hz), 110.6(d, J = 6.3 Hz), 27.7, 19.45 (d, J = 16.1 Hz), 15.6 (d, J = 13.9 Hz).

³¹P NMR (122 MHz, CDCb) 6 -62.0. HRMS (ESI+) m/z calculated for [CHHI₃O₂PH⁺] = 209.0726, found 209.0728.

I .XVI 11 Synthesis of furan-2-yldipropylphosphine

Dry and freshly activated magnesium powder (0.316 g, 13.0 mmol, 2.6 equiv.) was added to a round bottom flask and the system was flamed under vacuum. After cooling down the system, Et2O (15 mL, 0.33 mol/L) was added under argon. To this stirring solution, n- propylbromide (2.2 equiv., 11.0 mmol) was added dropwise. The reaction was stirred for 2h at room temperature, while it was possible to see consumption of powder magnesium and evolution of bubbles (if this is not visible, one can warm up the reactional mixture with hands or with slightly warm water). Then, it was cooled down to -78°C and furan-2-yl dichloro(furan-2-yl)phosphine (0.8447 g, 5 mmol, 1.0 equiv.) was added dropwise. The reaction was slowly warmed up to room temperature and it was stirred overnight. After this period, the reaction was filtered in a 22 pL filter under argon, the solvent was removed under vacuum, and distillation under vacuum afforded the desired product as a colorless oil (320.9 mg, 1 .74 mmol; q: 35%).

¹H NMR (300 MHz, CDCb) 6 7.60 (dd, J = 1 .8, 0.7 Hz, 1 H), 6.66 (ddd, J = 3.2, 2.0, 0.7 Hz, 1 H), 6.36 (ddd, J = 3.1 , 1 .8, 1 .1 Hz, 1 H), 1 .90 -1 .76 (m, 2H), 1 .59 (dddd, J = 13.4, 9.7, 6.0, 3.6 Hz, 2H), 1 .50 -1 .29 (m, 4H), 0.96 (t, J = 7.3 Hz, 6H).

¹³C NMR (75 MHz, CDCb) 6 154.9(d, J = 28.4 Hz), 146.4, 119.6 (d, J = 24.4 Hz), 110.3(d, J = 5.9 Hz), 29.1 (d, J = 6.4 Hz), 19.7(d, J = 13.6 Hz), 15.9(d, J = 12.2 Hz).

³¹P NMR (122 MHz, CDCb) 6 -45.1 .

HRMS (ESI+) m/z calculated for [CIOHI₇OPH⁺] = 185.1090, found 185.1088.

I .XIX Synthesis of difuran-2-yl)(neopentyl)phosphine

Dry and freshly activated magnesium powder (0.158 g, 6.5 mmol, 1 .3 equiv.) was added to a round bottom flask and the system was flamed under vacuum. After cooling down the system, Et₂O (15 mL, 0.33 mol/L) was added under argon. To this stirring solution, neo- pentylbromide (1.1 equiv., 5.5 mmol) was added dropwise. The reaction was stirred for 2h at room temperature, while it was possible to see consumption of powder magnesium and evolution of bubbles (if this is not visible, one can warm up the reactional mixture with hands or with slightly warm water). Then, it was cooled down to -78°C and chlorodi(furan-2- yl)phosphine(1 .028 g, 5 mmol, 1.0 equiv.) was added dropwise. The reaction was slowly warmed up to room temperature and it was stirred overnight. After this period, the reaction was filtered in a 22 pL filter under argon, the solvent was removed under vacuum, and distillation under vacuum afforded the desired product as a colorless oil (279.1 mg, 1.18 mmol, q: 24%).

¹H NMR (300 MHz, CDCb) 6 7.61 (dd, J = 1 .8, 0.7 Hz, 2H), 6.69 (ddd, J = 3.3, 2.0, 0.8 Hz, 2H), 6.36 (dt, J = 3.3, 1 .7 Hz, 2H), 2.24 (d, J = 3.3 Hz, 2H), 0.97 (d, J = 1 .1 Hz, 9H).

¹³C NMR (75 MHz, CDCb) 6 152.8(d, J = 16.3 Hz), 146.7(d, J = 1.5 Hz), 1 19.6(d, J = 25.8 Hz), 110.7 (d, J = 6.4 Hz), 40.7(d, J = 4.2 Hz), 31 .1 (d, J = 13.2 Hz), 30.5 (d, J = 9.1 Hz).

³¹P NMR (122 MHz, CDCb) 6 -69.1 .

HRMS (ESI+) m/z calculated for [Ci₃Hi7O₂PH⁺] = 237.1039, found 237.1041. I. XX Synthesis of difuran-2-yl)(propyl)phosphine oxide

To a solution of di(furan-2-yl)(propyl)phosphine (1.0 equiv., 1.7 mmol) in dichloromethane (~15 mL) in a flask with a magnetic stirred bar was slowly added aqueous solution of H2O2 (70 equiv., 30 wt%). The mixture was stirred for 3 hours at room temperature. After that time, the layers were separated and the organic phase was washed with water (2 x 30 mL) and it was dried over Na2SC>4. The solvent was evaporated under reduced pressure and the crude product was purified by column chromatography, resulting in the desired product in 75% yield as a white solid (276.1 mg, 1 .23 mmol, q: 74%). ¹H NMR (300 MHz, CDCb) 6 7.60 (ddd, J = 2.5, 1 .7, 0.7 Hz, 2H), 7.02 (ddd, J = 3.5, 1 .8, 0.7 Hz, 2H), 6.43 (ddd, J = 3.5, 1 .7, 1 .3 Hz, 2H), 2.27 -2.15 (m, 2H), 1 .68 -1 .53 (m, 2H), 0.95 (td, J = 7.4, 1.1 Hz, 3H).

¹³C NMR (75 MHz, CDCb) 6 147.9 (d, J = 7.7 Hz), 147.4 (d, J = 138.4 Hz), 121.7 (d, J = 18.6 Hz), 110.9 (d, J = 8.4 Hz), 31 .5 (d, J = 80.1 Hz), 15.3 (d, J = 16.1 Hz), 14.7 (d, J = 4.1 Hz).

³¹P NMR (122 MHz, CDCb) 6 12.2.

HRMS (ESI+) m/z calculated for [CHHI₃O₃PH⁺] = 225.0675, found 225.0672.

I. XXI Synthesis of furan-2-yldiphenylphosphine Under argon atmosphere, chlorodiphenylphosphine (1 .50 g, 6.80 mmol, 1 eq.) was charged in a flame dried Schlenk flask. Then, 15 ml anhydrous diethyl ether were added. In another Schlenk flask degassed furan (0.46 g, 6.80 mmol, 1 eq.) was dissolved in 10 ml anhydrous diethyl ether. The solution was cooled to -78 °C and n-Buli (2.5 M, 2.72 ml, 6.80 mmol, 1 eq.) was dropwise added to the solution with a syringe. Next, the reaction mixture was allowed to warm up to room temperature and stirred for 2 h. The reaction mixture was transferred in a Schlenk dropping funnel and the solution was slowly added to the chlorodiphenylphosphine solution at -78 °C. The solution was allowed to warm up to room temperature and stirred overnight. The resulting reaction mixture was filtrated through a syringe filter to remove the lithium chloride. Then, the solvent was removed in vacuo from the collected filtrate, which yielded a yellow oil. Finally, a colorless oil was obtained by high vacuum distillation, which crystallized shortly after the distillation (1.41 g, 5.58 mmol, q: 82%).

¹H NMR (400 MHz, THF-da): 6 = 7.74 (dd, J = 1 .9, 0.8, 1 H), 7.38 - 7.32 (m, 4H), 7.32 - 7.27 (m, 6H), 6.69 - 6.63 (m, 1 H), 6.44 (dt, J = 3.2, 1 .6, 1 H).

¹³C NMR (101 MHz, THF-da): 6 = 153.25 (d, J=18.1), 148.51 (d, J=1 .7), 137.43 (d, J=6.3), 133.90 (d, J=19.8), 129.32, 128.97 (d, J=7.0), 122.39 (d, J=24.7), 111 .16 (d, J=5.5).

³¹P NMR (122 MHz, THF-da): 6 = -27.12.

GC-MS: m/z (%): 253.08 ([M+H]⁺, 18), 252.08 (M+, 100), 251.08 ([M-H]⁺, 19), 205.10 (1 1), 204.10 (9), 203.09 (9), 183.02 (17), 175.02 (41), 147.02 (9), 146.02 (10), 145.01 (16), 144.03 (10), 128.04 (10), 1 15.04 (16), 107.99 (12), 106.99 (13), 105.01 (7).

I. XXI I Synthesis of tris(5-methylfuran-2-yl)phosphine

A flame dried Schlenk flask was charged with degassed 2-methylfuran (2.28 g, 27.71 mmol, 3.3 eq.) and 20 ml of anhydrous THF. Then, n-Buli (2.5 M, 11 .1 ml, 27.75 mmol, 3.3 eq.) was added dropwise to the solution at -78 °C and the temperature was kept for 1 h. The reaction mixture was allowed to warm up to room temperature slowly and stirred for 2 h. Next, the reaction mixture was cooled again to -78 °C and phosphorus trichloride (1.15 g, 8.39 mmol, 1 eq.) was slowly injected. After, the reaction mixture was allowed to warm up to room temperature and stirred overnight, the solvent was removed in vacuo. In order to remove the lithium chloride, the brownish product was dissolved in anhydrous Et2O and was filtrated with a syringe filter. The collected filtrate was then concentrated and crystallization was achieved at -20 °C. After, two recrystallization processes colourless crystals were obtained, which were dried with high vacuum (1 .65 g, 6.02 mmol, q: 72%).

¹H NMR (400 MHz, THF-da): 6 = 6.60 (ddd, J=3.2, 1 .6, 0.5, 3H), 5.99 (dt, J=3.2, 1 .2, 3H), 2.27 (d, J=1 .1 , 9H).

¹³C NMR (101 MHz, THF-da): 6 = 157.66 (d, J=3.4), 148.70 (d, J=2.0), 122.22 (d, J=21 .1), 107.59 (d, J=5.4), 13.50.

³¹P NMR (162 MHz, THF-da): 6 = -76.41 .

GC-MS: m/z (%): 275.11 ([M+H]⁺, 17), 274.1 1 (M+, 100), 273.1 1 ([M-H]⁺, 3), 231 .08 (10), 213.08 (5), 212.11 (6), 211.13 (5), 210.13 (5), 195.09 (8), 193.06 (6), 185.10 (7), 184.10 (6), 180.05 (5), 174.08 (12), 169.08 (5), 167.09 (8), 166.04 (19), 163.08 (8), 162.08 (60), 161 .08 (17) 159.06 (9), 151 .03 (9), 145.08 (8), 119.05 (14), 1 12.01 (20), 96.99 (13).

I .XXII I Synthesis of bis(furan-2-yl)(methyl)phosphine

Under argon atmosphere, bis(2-furyl)-phosphine chloride (0.55 g, 2.74 mmol, 1 eq.) was weighted in a flame dried Schlenk flask. Then, 15 ml anhydrous diethyl ether were added and the solution was cooled to -78 °C. Methyllithium (1 .6 M, 1 .71 ml, 2.74 mmol, 1 eq.) was slowly transferred to the stirring solution and the temperature was kept at -78 °C for 1 h. The reaction mixture was allowed to warm up to room temperature and stir over night. After, the lithium chloride was removed from the reaction mixture by anaerobic filtration with a syringe filter, the solvent was removed in vacuo. Finally, the received yellow oil was purified by vacuum distillation, which yielded the target product as a colourless oil (0.34 g, 2.74 mmol, q: 69%). ¹H NMR (400 MHz, THF-da): 6 = 7.65 (dd, J = 1 .7, 0.7, 2H), 6.73 - 6.58 (m, 2H), 6.45 - 6.27 (m, 2H), 1.59 (d, J = 4.2, 3H).

¹³C NMR (101 MHz, THF-da): 6 = 153.66 (d, J=16.2), 147.51 (d, J=1 .5), 119.22 (d, J=23.9), 111 .00 (d, J=5.4), 9.35 (d, J=3.7).

³¹P NMR (162 MHz, THF-da): 6 = -70.02.

GC-MS: m/z (%): 181.05 ([M+H]⁺, 7), 180.04 (M⁺, 70), 166.02 (9), 165.02 (100), 137.02 (14), 136.01 (6), 118.04 (7), 109.02 (45), 107.01 (5), 83.01 (13), 81.02 (5), 70.01 (6), 69 (9), 68 (4), 65.04 (5), 57.01 (9).

I .XXIV Synthesis of bis(furan-2-yl)(phenyl)phosphine

Bis(furan-2-yl)(phenyl)phosphine was synthesized by the same method as described for bis(furan-2-yl)(methyl) phosphine. The desired product was received by the reaction of phenyllithium (1.9 M, 2.67 ml, 5.08 mmol, 1 eq.) and bis(2-furyl)-phosphine chloride (1.02 g, 5.08 mmol, 1 eq.) as a colourless oil (1 .05 g, 4.34 mmol, q: 85%).

¹H NMR (400 MHz, THF-da): 6 = 7.73 (dt, J=1 .8, 0.6, 2H), 7.42 - 7.34 (m, 2H), 7.31 - 7.25 (m, 3H), 6.72 (ddd, J=3.3, 1.7, 0.8, 2H), 6.44 (dt, J=3.3, 1.6, 2H).

¹³C NMR (101 MHz, THF-da): 6 = 151.59 (d, J=9.0), 148.37 (d, J=2.7), 136.04 (d, J=2.2), 133.15 (d, J=20.1), 129.35, 128.91 (d, J=7.2), 121.82 (d, J=23.3), 11 1.22 (d, J=5.8).

³¹P NMR (162 MHz, THF-da): 6 = -51.18.

GC-MS: m/z (%): 243.08 ([M+H]⁺, 16), 242.08 (M⁺, 100), 241.08 ([M-H]⁺, 7), 195.08 (5), 183.05 (7), 179.09 (7), 178.09 (11), 177.08 (6), 167.09 (14), 166.08 (11), 162.03 (17), 152.06 (14), 145.03 (11), 144.05 (14), 134.03 (7), 128.06 (9), 115.06 (19), 109.02 (12), 108.01 (8), 107.00 (14), 105.02 (8), 97.99 (9), 77.05 (11), 70.00 (9), 51 .04 (8). I. XXV Synthesis of A/,A/-diethyl-1 ,1-di(furan-2-yl)phosphanamine

First, a flame dried Schlenk flask was charged with degassed furan (1 .47 g, 21 .65 mmol, 2.1 eq.) and then 15 ml anhydrous diethyl ether were added. The solution was cooled to - 78 °C, followed by the slowly addition of n-Buli (2.5 M, 8.66 ml, 21 .65 mmol, 2.1 eq.) with a syringe. The reaction mixture was allowed to warm up to room temperature and stirred for 2 h. Dichloro(diethylamino)phosphine (1.80 g, 10.31 mmol, 1 eq.) was weighted in a separate Schlenk flask and was dissolved in 15 ml anhydrous diethyl ether. Next, the lithiated furan solution was transferred into a Schlenk dropping funnel and the solution was dropwise added to the dichloro(diethylamino)phosphine solution at -78 °C. The reaction mixture was allowed to warm up to room temperature overnight. The resulting brown suspension was filtrated with a syringe filter. Then, the solvent was removed in vacuo, which yielded a brown oil. Finally, the product (1.66 g, 7.00 mmol, q: 68%) was obtained as a colourless oil by vacuum distillation of the crude oil.

¹H NMR (400 MHz, THF-da): 6 = 7.69 (dd, J=1 .7, 0.8, 1 H), 6.59 (dt, J=3.3, 0.6, 1 H), 6.41 (dt, J=3.2, 1.5, 1 H), 3.11 (dq, J=10.3, 7.0, 4H), 0.94 (t, J=7.1 , 6H).

¹³C NMR (101 MHz, THF-da): 6 = 155.91 (d, J=9.8), 146.95 (d, J=3.6), 119.06 (d, J=21.0), 110.81 (d, J=4.0), 45.07 (d, J=16.2), 14.57 (d, J=3.8).

³¹P NMR (162 MHz, THF-da): 6 = 13.68.

GC-MS: m/z (%): 238.13 ([M+H]⁺, 6), 237.13 (M⁺, 41), 222.10 (13), 194.06 (5), 166.04 (11), 165.06 (100), 156.07 (14), 139.09 (4), 137.03 (7), 109.03 (17), 99.01 (9), 83.01 (5), 74.03 (4), 71.03 (4), 70.03 (4). I .XXVI Synthesis of tri(benzofuran-2-yl)phosphine

Tri(benzofuran-2-yl)phosphine was synthesized according to the literature with some modifications. Under argon atmosphere, anhydrous benzofuran (2.52 g, 21 .35 mmol, 3 eq.) was dissolved in 30 ml of anhydrous THF. The solution was cooled to -20 °C and then n- BuLi (2.5 mM, 8.54 ml, 21.35 mmol, 3 eq.) was slowly added. The yellow solution was allowed to warm up to room temperature and stir for 2 h. Next, the reaction mixture was cooled again to -20 °C and phosphorus trichloride (978 mg, 7.12 mmol, 1 eq.) was slowly added. The reaction temperature was kept at -20 °C for 1 h, before the solution was warmed up to room temperature. After, overnight stirring the yellowish suspension was filtrated with a syringe filter, yielding a yellow solution. Then, the solvent was re-moved in vacuo and a yellow solid was obtained. Column chromatography was per-formed using n-hexane and 5% ethyl acetate. Finally, the desired product was obtained as a white powder after the solvent was removed in vacuo (1 .99 g, 5.20 mmol, q: 73%).

¹H NMR (400 MHz, THF-da): 6 = 7.60 (dt, J = 7.8, 1 .2, 3H), 7.52 (dt, J = 8.3, 1 .0, 3H), 7.36 - 7.26 (m, 6H), 7.21 (td, J = 7.6, 1.1 , 3H).

¹³C NMR (101 MHz, THF-da): 6 = 158.99 (d, J=3.6), 151.86 (d, J=3.8), 128.77 (d, J=6.2), 126.23, 123.67, 122.10, 118.86 (d, J=21.4), 112.09.

³¹P NMR (122 MHz, THF-da): 6 = -67.32.

GC-MS: m/z (%): 383.05 ([M+H]⁺, 22), 382.05 (M⁺, 85), 381.05 ([M-H]⁺, 13), 318.06 (4), 291.07 (5), 289.01 (9), 276.01 (6), 265.00 (5), 263.99 (16), 263.01 (5), 246.03 (9), 236.02 (7), 235.04 (18), 234.04 (100), 218.04 (9), 207.00 (9), 205.03 (16), 189.03 (18), 176.02 (6), 148.97 (6), 147.97 (58), 119.97 (28), 89.00 (5), 62.99 (5). I. XXVI I Synthesis of n-Butyldi(furan-2-yl)phosphine

/V-butyl lithium (1.1 equiv.) was added under argon to a solution of chlorodi(furan-2- yl)phosphine (1.028 g, 5 mmol, 1 .0 equiv.)in Et2O (15 mL, 0.33 mol/L)at -78°C and it was stirred for 2h. The reaction was slowly warmed up to rt and it was stirred overnight. After this period, the reaction was filtered in a 22 pL filter under Argon, the solvent was removed under vacuum, and distillation under vacuum afforded the desired product as a colorless oil (873.6 mg, 3.9mmol, q: 78%).

¹H NMR (300 MHz, CDCb) 6 7.62 (dd, J = 1 .8, 0.7 Hz, 2H), 6.72 (ddd, J = 3.2, 1 .9, 0.8 Hz, 2H), 6.38 (dt, J = 3.3, 1 .6 Hz, 2H), 2.20 -2.10 (m, 2H), 1 .39 (ddt, J = 6.3, 5.2, 2.0 Hz, 4H),

0.93 -0.83 (m, 3H).

¹³C NMR (75 MHz, CDCb) 6 152.0(d, J = 17.4 Hz), 146.9 (d, J = 1.5 Hz), 120.0 (d, J = 24.6 Hz), 110.6(d, J = 6.2 Hz), 28.1 (d, J = 15.3 Hz), 25.17, 24.0 (d, J = 13.7 Hz), 13.8.

³¹P NMR (122 MHz, CDCb) 6 -61 .3. HRMS (ESI+) m/z calculated for [CI₂HI₅O₂PH⁺] = 223.0883, found 223.0886.

I.XXVIII Synthesis of f-Butyldi(furan-2-yl)phosphine f-butyl lithium (1.1 equiv.) was added under argon to a solution of chlorodi(furan-2- yl)phosphine (1.028 g, 5 mmol, 1.0 equiv.)in Et2O (15 mL, 0.33 mol/L)at -78°C and it was stirred for 2h. The reaction was slowly warmed up to rt and it was stirred overnight. After this period, the reaction was filtered in a 22 pL filter under Argon, the solvent was removed under vacuum, and distillation under vacuum afforded the desired product as a colorless oil (666.66 mg, 3.0mmol, q: 60%).

¹H NMR (400 MHz, CDCb) 6 7.69 (dt, J = 1 .8, 0.6 Hz, 2H), 6.83 (ddd, J = 3.1 , 2.2, 0.8 Hz, 2H), 6.42 (dt, J = 3.2, 1.6 Hz, 2H), 1.11 (d, J = 14.0 Hz, 9H).

¹³C NMR (101 MHz, CDCb) 6 150.9 (d, J = 15.6 Hz), 147.0 (d, J = 1.8 Hz), 122.2(d, J = 23.0 Hz), 110.5 (d, J = 6.6 Hz), 32.4(d, J = 5.9 Hz), 28.3(d, J = 14.9 Hz).

³¹P NMR (162 MHz, CDCb) 6 -29.7.

HRMS (ESI+) m/z calculated for [CI₂HI₅O₂PH⁺] = 223.0883, found 223.0886.

I. XXIX Synthesis of tri(benzofuran-2-yl)phosphine oxide

A 100 ml round bottom flask was charged with tri(benzofuran-2-yl)phosphine (268 mg, 0.7 mmol, 1 eq.) and a stirring bar. After, the addition of 30 ml DCM, hydrogen peroxide (30 wt%, 49 mmol, 70 eq.) was slowly injected while stirring. The reaction mixture was allowed to stir for 3 h at room temperature. Then, the mixture was transferred into a separating funnel and the organic layer was washed twice with water. After, the organic phase was dried with sodium sulphate, the solvent was evaporated. [12] Finally, a white solid was obtained after column chromatography (163 mg, 0.41 mmol, q: 58%).

¹H NMR (400 MHz, THF) 6 = 7.78 - 7.68 (m, 6H), 7.59 (dq, J=8.4, 0.9, 3H), 7.48 - 7.39 (m, 3H), 7.31 (ddd, J=8.0, 7.2, 0.9, 3H). ¹³C NMR (101 MHz, THF) 6 = 158.85, 158.75, 150.06, 148.57, 127.93, 127.62, 127.52, 124.39, 123.33, 120.75, 120.54, 112.75.

³¹P NMR (162 MHz, THF) 6 = -11 .96.

GC-MS: m/z (%): 399.10 ([M+H]⁺, 8), 398.10 (M⁺, 30), 382.10 (9), 266.06 (18), 265.06 (100), 236.06 (9), 235.08 (7), 234.08 (38), 218.09 (11), 207.05 (16), 205.07 (13), 189.08 (12), 176.07 (6), 148.00 (9), 120.01 (8), 89.03 (11), 63.04 (8).

II. In situ synthesis of coordination complexes according to the invention comprising cobalt as a coordination centre and screening of their catalytic activity for the isomerization of A/.M-diethylgeranylamine to citronellal enamine

11.1 General procedure

Under argon atmosphere, an oven-dried 25 mL Schlenk tube was charged with a cobalt(ll) precursor coordination complex (kind/amount as indicated in Table 1 below), a selected compound of formula (I) as defined herein (ligands as shown in Scheme 3 below in an amount as indicated in Table 1 below) and a stirring bar. Then, the Schlenk tube was sealed with a rubber septum and 2 mL of anhydrous solvent as indicated in Table 1 below were added. The solution was allowed to stir for approximately 2 min. At room temperature, 0.2 mL of a DIBAL-THF-solution (with an amount of DIBAL as indicated in Table 1 below) was injected dropwise to the solution under stirring. The substrate, N,N- diethylgeranylamine (0.523 g, 2.5 mmol) was added to the solution and the Schlenk tube was sealed. The solution was heated for 24 h at 80 °C. Afterwards, the solution was cooled down to room temperature and the solvent was removed in vacuo. Finally, vacuum distillation of the obtained brown oil yielded the citronellal enamine. The conversion of N,N- diethylgeranylamine to citronellal enamine was determined by GC analysis using hexadecane as internal standard (cf. Table 1 below).

11.11 Optimized conditions for tri(benzofuran-2-yl)phosphine

Cobalt(ll) acetylacetonate (1.3 mg, 0.005 mmol, 1 eq.) and tri(benzofuran-2-yl)phosphine (3.8 mg, 0.01 mmol, 2 eq.) were charged together with a stirring bar in a 25 mL Schlenk tube. Under argon atmosphere, 1.5 mL of anhydrous 2-MeTHF were added. At room temperature, a DIBAL-toluene-solution (0.1 M, 0.1 mL, 0.01 mmol, 2 eq.) was injected dropwise into the stirring solution. Next, /V,/V-diethylgeranylamine (1.047 g, 5 mmol) was added to the solution and the Schlenk tube was sealed. The solution was heated for 24 h at 100 °C. Then, the solvent was removed in vacuo, yielding a brown oil. The citronellal enamine was obtained after vacuum distillation was performed. The further procedure is described in the general procedure above.

As it becomes apparent from Table 1 below, good conversion rates of A/,/V-diethyl- geranylamine to citronellal enamine can be achieved through catalysis by the coordination complexes according to the present invention, even at a low amounts of precursor coordination complex equivalents (Co(X)2).

Scheme 3: Compounds of formula (I) as defined herein used in the screening

Table 1: Results of the screening of the in situ generated coordination complexes according to the invention 11.111 Mechanistic investigations of the catalytic cycle by X-ray structure analysis

To get further insights into the possible structure of the catalytically active species, mechanistic investigations by X-ray structure analysis were conducted.

11.111.1 In a first experiment, Co(acac)2 was dissolved in THF and a solution of tri(benzofuran- 2-yl)phosphine (PR3) in THF was added dropwise to the [Co]-solution. Subsequently, the mixture was stirred for 4 h at room temperature and a precipitate crystallized at -40 °C (solvent-mixture: THF/n-hexane). This solid was investigated by X-ray structure analysis and it revealed that most likely a Co(ll) pre-species as shown in Figure 4 is formed.

THF thereby serves as co-ligand and the tri(benzofuran-2-yl)phosphine ligands should bind relatively weakly. This leads to the assumption that the coordination of the phosphine during the reaction is probably induced through the reduction of the metal and the increased temperature during reaction (80°C).

II. III. II In a second experiment, the procedure as described above was partly repeated. Thus, Co(acac)2 was dissolved in THF and a solution of tri(benzofuran-2-yl)phosphine (PR3) in THF was added dropwise to the [Co]-solution. DIBAL-H was slowly added and the reaction mixture was stirred for 2 h at -80°C. After crystallization at -80°C (solvent mixture: THF/n-hexane), the solid was investigated by X-ray structure analysis and revealed that most likely a Co(0) species with fourtri(benzofuran-2-yl)phosphine ligands (PR3) is formed (cf. Figure 5).

This is probably preceded by the rearrangement of the initially formed Co(l) and Co(0) species comprising inter alia two of the tri(benzofuran-2-yl)phosphine ligands (PR3).

III. In situ synthesis of coordination complexes according to the invention comprising rhodium as a coordination centre and screening of their catalytic activity for the isomerization of diethylgeranylamine to citronellal enamine

111.1 General procedure

An 8 mL glass vial was charged with a rhodium(l) precursor coordination complex (kind/amount as indicated in Table 2 below), a selected compound of formula (I) as defined herein (ligands as shown in Scheme 4 below in an amount as indicated in Table 2 below) and a stirring bar. The vial was then sealed with a plastic cap with a rubber septum and evacuated/flushed with argon gas a total of three times. Next, 1 .5 mL of anhydrous solvent as indicated in Table 2 below were added. The solution was allowed to stir for approximately 2 min. At room temperature, 0.1 mL of a DIBAL-THF solution (with an amount of DIBAL as indicated in Table 2 below) was injected dropwise to the solution under stirring and argon atmosphere. The solution was allowed to stir overnight at room temperature. The substrate, /V,/V-diethylgeranylamine (209.4 mg, 1.0 mmol) was added to the solution under stirring and argon atmosphere. The solution was heated for 48 h at 80 °C. Afterwards, the solution was cooled down to room temperature and the solvent was removed in vacuo. Finally, vacuum distillation of the obtained brown oil yielded the citronellal enamine. The conversion of /V,/V-diethylgeranylamine to citronellal enamine was determined by GC analysis using hexadecane as internal standard (cf. Table 2 below).

111.11 Optimized conditions for tri(benzofuran-2-yl)phosphine

Bis(1 ,5-cyclooctadiene)dirhodium(l) dichloride (12.3 mg, 0.025 mmol, 0.5 eq.) and tri(benzofuran-2-yl)phosphine (38.2 mg, 0.10 mmol, 2.0 eq.) were charged together with a stirring bar in an 8 mL glass vial. The vial was then sealed with a plastic cap with a rubber septum and evacuated/flushed with argon gas a total of three times. Under argon atmosphere, 1 .5 mL of anhydrous 2-MeTHF were added. At room temperature, a DIBAL- THF solution (1 M, 0.1 mL, 0.10 mmol, 2.0 eq.) was injected dropwise into the stirring solution. The solution was allowed to stir overnight at room temperature. Next, N,N- diethylgeranylamine (209.4 mg, 1 mmol) was added to the solution. The solution was heated for 48 h at 80 °C. Then, the solvent was removed in vacuo, yielding a brown oil. The citronellal enamine was obtained after vacuum distillation was performed. The further procedure is described in the general procedure above.

Scheme 4: Compounds of formula (I) as defined herein used in the screening

Table 2: Results of the screening of the in situ generated coordination complexes according to the invention

IV. In situ synthesis of coordination complexes according to the invention comprising ruthenium as a coordination centre and screening of their catalytic activity for the isomerization of AL/V-diethylqeranylamine to citronellal enamine

IV. I General procedure

Under argon atmosphere, an oven-dried 10 mL Schlenk pressure tube was charged with a ruthenium(l) precursor coordination complex (kind/amount as indicated in Table 3 below), a selected compound of formula (I) as defined herein (ligand as shown in Scheme 5 below in an amount as indicated in Table 3 below) and a stirring bar. Then, the Schlenk tube was sealed with a rubber septum and 1 .5 mL of anhydrous solvent as indicated in Table 3 below were added. The solution was allowed to stir for approximately 2 min. At room temperature, 0.1 mL of a DIBAL-THF solution (with an amount of DIBAL as indicated in Table 3 below) was injected dropwise to the solution under stirring. The Schlenk tube was sealed and the solution was allowed to stir overnight at room temperature. The substrate, N,N- diethylgeranylamine (209.4 mg, 1.0 mmol) was added to the solution under stirring and argon atmosphere. The solution was heated for 48 h at 120 °C. Afterwards, the solution was cooled down to room temperature and the solvent was removed in vacuo. Finally, vacuum distillation of the obtained brown oil yielded the citronellal enamine. The conversion of /V,/V-diethylgeranylamine to citronellal enamine was determined by GC analysis using hexadecane as internal standard (cf. Table 3 below).

IV.11 Optimized conditions for tri(2-furyl)phosphine

Dichloro(benzene)ruthenium(ll) dimer (12.5 mg, 0.025 mmol, 0.5 eq.) and tri(2- furyl)phosphine (23.2 mg, 0.10 mmol, 2.0 eq.) were charged together with a stirring bar in an 10 mL Schlenk pressure tube. Under argon atmosphere, 1 .5 mL of anhydrous 2-MeTHF were added. At room temperature, a DIBAL-THF solution (1 M, 0.1 mL, 0.10 mmol, 2.0 eq.) was injected dropwise into the stirring solution. The solution was allowed to stir overnight at room temperature. Next, /V,/V-diethylgeranylamine (209.4 mg, 1 mmol) was added to the solution. The solution was heated for 48 h at 120 °C. Then, the solvent was removed in vacuo, yielding a brown oil. The citronellal enamine was obtained after vacuum distillation was performed. The further procedure is described in the general procedure above.

Scheme 5: Compound of formula (I) as defined herein used in the screening

Table 3: Results of the screening of the in situ generated coordination complex according to the invention

V. In situ synthesis of coordination complexes according to the invention comprising iridium as a coordination centre and screening of their catalytic activity for the isomerization of AL/V-diethyloeranylamine to citronellal enamine

V.l General procedure

An 8 mL glass vial was charged with an iridium(l) precursor coordination complex (kind/amount as indicated in Table 4 below), a selected compound of formula (I) as defined herein (ligand as shown in Scheme 6 below in an amount as indicated in Table 4 below) and a stirring bar. The vial was then sealed with a plastic cap with a rubber septum and evacuated/flushed with argon gas a total of three times. Next, 1 .5 mL of anhydrous solvent as indicated in Table 4 below were added. The solution was allowed to stir for approximately 2 min. At room temperature, 0.1 mL of a DIBAL-THF solution (with an amount of DIBAL as indicated in Table 4 below) was injected dropwise to the solution under stirring and argon atmosphere. The solution was allowed to stir overnight at room temperature. The substrate, /V,/V-diethylgeranylamine (209.4 mg, 1.0 mmol) was added to the solution under stirring and argon atmosphere. The solution was heated for 48 h at 80 °C. Afterwards, the solution was cooled down to room temperature and the solvent was removed in vacuo. Finally, vacuum distillation of the obtained brown oil yielded the citronellal enamine. The conversion of /V,/V-diethylgeranylamine to citronellal enamine was determined by GC analysis using hexadecane as internal standard (cf. Table 4 below).

V.ll Optimized conditions for tri(benzofuran-2-yl)phosphine

Bis(1 ,5-cyclooctadiene)diiridium(l) dichloride (33.6 mg, 0.050 mmol, 1.0 eq.) and tri(benzofuran-2-yl)phosphine (38.2 mg, 0.10 mmol, 2.0 eq.) were charged together with a stirring bar in an 8 mL glass vial. The vial was then sealed with a plastic cap with a rubber septum and evacuated/flushed with argon gas a total of three times. Under argon atmosphere, 1 .5 mL of anhydrous 2-MeTHF were added. At room temperature, a DIBAL- THF solution (1 M, 0.1 mL, 0.10 mmol, 2.0 eq.) was injected dropwise into the stirring solution. The solution was allowed to stir overnight at room temperature. Next, N,N- diethylgeranylamine (209.4 mg, 1 mmol) was added to the solution. The solution was heated for 48 h at 80 °C. Then, the solvent was removed in vacuo, yielding a brown oil. The citronellal enamine was obtained after vacuum distillation was performed. The further procedure is described in the general procedure above.

Scheme 6: Compound of formula (I) as defined herein used in the screening Table 4: Results of the screening of the in situ generated coordination complex according to the invention

Claims

Claims:

1 . Coordination complex obtained or obtainable by a process comprising or consisting of the following steps: a) Providing a precursor coordination complex, wherein the coordination centre of the precursor coordination complex is a rhodium, ruthenium, palladium, iridium, manganese, iron, cobalt, or nickel atom or is a rhodium, ruthenium, palladium, iridium, manganese, iron, cobalt, or nickel ion or is a 3d transition metal atom or ion, b) providing a compound of formula (I) wherein R¹ is a residue independently selected from the group consisting of or R¹ is a residue according to formula (II) wherein R³, R⁴, and R⁵ are independently selected from the group consisting of H, alkyl, or aryl, and/or R³ forms an aromatic ring with R⁴ and/or R⁴ forms an aromatic ring with R⁵, and wherein R² is a residue selected from the group consisting of or R² is a residue according to formula (II) wherein R³, R⁴, and R⁵ are independently selected from the group consisting of H, alkyl, or aryl, and/or R³ forms an aromatic ring with R⁴ and/or R⁴ forms an aromatic ring with R⁵, and wherein

- in case R¹ is , R² is not or vice versa, and

- in case both of R¹ and R² are then the coordination centre of the precursor coordination complex provided in step a) is not a rhodium atom or ion, c) producing a solution or suspension comprising the precursor coordination complex provided in step a), the compound of formula (I) provided in step b), and one or more solvent(s), preferably one or more non-polar solvent(s), more preferably wherein the one or more solvents) is/are selected from the group consisting of tetrahydrofuran, 2-methyltetrahydrofuran, toluene, cyclohexane, benzene, xylene, dibutyl ether, dioxane, hexane, and heptane, d) adding, preferably dropwise or portionwise, one or more reducing agent(s) to the solution or suspension produced in step c), preferably wherein the one or more reducing agent(s) is/are selected from the group consisting of diisobutylaluminium hydride, triethylaluminium, diisobutylaluminium hydride- tetrahydrofuran-solution, diisobutylaluminium hydride-toluene-solution, aluminium hydride, /V,/V-dimethylethylamine complex, lithium diisobutyl-tert- butoxyaluminium hydride, lithium aluminium hydride, sodium borohydride, and sodium triethylborohydride, e) optionally, isolating the coordination complex formed in step d) from the reaction mixture.

2. Coordination complex obtained or obtainable by a process according to claim 1 , wherein the compound of formula (I) provided in step b) is selected from the group consisting of

L30

3. Coordination complex obtained or obtainable by a process according to claim 1 , 2 or 15, wherein the molar ratio of the compound(s) of formula (I) and/or (IV) to the precursor coordination complex in the solution or suspension produced in step c) is in a range of from 1 to 10, preferably from 1 to 5, more preferably is equal to or greater than 1.

4. Process for producing a coordination complex, preferably as defined in any of the claims 7 to 10, comprising or consisting of the following steps: a) Providing a precursor coordination complex, wherein the coordination centre of the precursor coordination complex is a rhodium, ruthenium, palladium, iridium, manganese, iron, cobalt, or nickel atom or is a rhodium, ruthenium, palladium, iridium, manganese, iron, cobalt, or nickel ion or is a 3d transition metal atom or ion, b) providing a compound of formula (I) wherein R¹ is a residue independently selected from the group consisting of or R¹ is a residue according to formula (II) wherein R³, R⁴, and R⁵ are independently selected from the group consisting of H, alkyl, or aryl, and/or R³ forms an aromatic ring with R⁴ and/or R⁴ forms an aromatic ring with R⁵, and wherein R² is a residue selected from the group consisting of or R² is a residue according to formula (II) wherein R³, R⁴, and R⁵ are independently selected from the group consisting of H, alkyl, or aryl, and/or R³ forms an aromatic ring with R⁴ and/or R⁴ forms an aromatic ring with R⁵, and wherein

- in case R¹ is , R² is not or vice versa, and

- in case both of R¹ and R² are then the coordination centre of the precursor coordination complex provided in step a) is not a rhodium atom or ion, c) producing a solution or suspension comprising the precursor coordination complex provided in step a), the compound of formula (I) provided in step b), and one or more solvent(s), preferably one or more non-polar solvent(s), more preferably wherein the one or more solvent(s) is/are selected from the group consisting of tetrahydrofuran, 2-methyltetrahydrofuran, toluene, cyclohexane, benzene, xylene, dibutyl ether, dioxane, hexane, and heptane, d) adding, preferably dropwise or portionwise, one or more reducing agent(s) to the solution produced in step c), preferably wherein the one or more reducing agent(s) is/are selected from the group consisting of diisobutylaluminium hydride, triethylaluminium, diisobutylaluminium hydride-tetrahydrofuran- solution, diisobutylaluminium hydride-toluene-solution, aluminium hydride, /V,/V-dimethylethylamine complex, lithium diisobutyl-tert-butoxyaluminium hydride, lithium aluminium hydride, sodium borohydride, and sodium triethylborohydride, and e) optionally, isolating the coordination complex formed in step d) from the reaction mixture.

5. Process according to claim 4, wherein the compound of formula (I) is selected from the group consisting of

6. Process according to claim 4 or 5, wherein the molar ratio of the compound of formula (I) to the precursor coordination complex in the solution produced in step c) is in a range of from 1 to 10, preferably from 1 to 5, more preferably is equal to or greater than 1.

7. Coordination complex, preferably obtained or obtainable according to a process as defined in any of the claims 1 to 6 and 15, wherein one, two, three, four or more of the compounds of formula (I) and/or (IV) as defined in any of the claims 1 , 2, 4, 5 and 15, preferably as defined in claim 2 or 5, are bound as ligand(s) to the coordination centre of the coordination complex by one, two or more coordinative bond(s), respectively, and optionally wherein one, two, three, four or more further ligand(s) selected from the group consisting of H, solvent molecules and ligands of a precursor coordination complex are bound to the coordination centre of the coordination complex by one, two or more coordinative bond(s), respectively.

8. Coordination complex according to claim 7, wherein the coordination centre of the coordination complex is a rhodium, ruthenium, palladium, iridium, manganese, iron, cobalt, or nickel atom or is a rhodium, ruthenium, palladium, iridium, manganese, iron, cobalt, or nickel ion or is a 3d transition metal atom or ion.

9. Coordination complex according to claim 7 or 8, wherein the one or more solvent molecule(s) that is/are bound to the coordination centre of the coordination complex by one, two or more coordinative bond(s), respectively, is/are one or more non-polar solvent molecule(s), preferably is/are selected from the group consisting of tetrahydrofuran, 2-methyltetrahydrofuran, toluene, cyclohexane, benzene, xylene, dibutyl ether, dioxane, hexane, and heptane.

10. Coordination complex according to any of the claims 7 to 9, wherein the one or more ligand(s) of the precursor coordination complex that is/are bound to the coordination centre of the coordination complex by one, two or more coordinative bond(s), respectively, is/are bidentate ligand(s), preferably is/are selected from the group consisting of acetylacetonate, acetate, naphthenate, benzoate, 2-ethylhexanoate, chloride, bromide, trifluoromethanesulfonate, 1 ,2-dimethoxyethane, 2, 2,6,6- tetramethyl-3,5-heptanedionate, hexafluoroacetylacetonate, and trifluoroacetylacetonate.

11. Use of a coordination complex obtained or obtainable according to a process as defined in any of the claims 1 to 6 and 15 or as defined in any of the claims 7 to 10 as a catalyst, preferably in a hydrogen transfer reaction, more preferably for the isomerization of a double bond in a substrate.

12. Use according to claim 11 , wherein the substrate to be isomerized comprises two or more double bonds, preferably wherein only one of the double bonds is isomerized.

13. Use according to claim 11 or 12, wherein the substrate to be isomerized further comprises one or more heteroatom(s), preferably further comprises one or more nitrogen atom(s).

14. Process, preferably hydrogen transfer reaction, more preferably for the isomerization of a double bond in a substrate, comprising or consisting of the following steps: a) Providing a coordination complex obtained or obtainable according to a process as defined in any of the claims 1 to 6 and 15 or as defined in any of the claims 7 to 10, b) providing a substrate, preferably wherein the substrate comprises two or more double bonds, c) contacting the coordination complex provided in step a) with the substrate provided in step b), and d) carrying out a catalytic reaction, preferably an isomerization reaction, on the substrate catalyzed by the coordination complex.

15. Coordination complex obtained or obtainable by a process comprising or consisting of the following steps: a) Providing a precursor coordination complex, wherein the coordination centre of the precursor coordination complex is a rhodium, ruthenium, palladium, iridium, manganese, iron, cobalt, or nickel atom or is a rhodium, ruthenium, palladium, iridium, manganese, iron, cobalt, or nickel ion or is a 3d transition metal atom or ion, b) providing a compound of formula (IV)

(IV), wherein R¹ is a residue independently selected from the group consisting of or R¹ is a residue according to formula (II) wherein R³, R⁴, and R⁵ are independently selected from the group consisting of H, alkyl, or aryl, and/or R³ forms an aromatic ring with R⁴ and/or R⁴ forms an aromatic ring with R⁵, and wherein R² is a residue selected from the group consisting of or R² is a residue according to formula (II) wherein R³, R⁴, and R⁵ are independently selected from the group consisting of H, alkyl, or aryl, and/or R³ forms an aromatic ring with R⁴ and/or R⁴ forms an aromatic ring with R⁵, and wherein then the coordination centre of the precursor coordination complex provided in step a) is not a rhodium atom or ion, c) producing a solution or suspension comprising the precursor coordination complex provided in step a), the compound of formula (IV) provided in step b), and one or more solvent(s), preferably one or more non-polar solvent(s), more preferably wherein the one or more solvent(s) is/are selected from the group consisting of tetrahydrofuran, 2-methyltetrahydrofuran, toluene, cyclohexane, benzene, xylene, dibutyl ether, dioxane, hexane, and heptane, d) adding, preferably dropwise or portionwise, one or more reducing agent(s) to the solution or suspension produced in step c), preferably wherein the one or more reducing agent(s) is/are selected from the group consisting of diisobutylaluminium hydride, triethylaluminium, diisobutylaluminium hydride- tetrahydrofuran-solution, diisobutylaluminium hydride-toluene-solution, aluminium hydride, /V,/V-dimethylethylamine complex, lithium diisobutyl-tert- butoxyaluminium hydride, lithium aluminium hydride, sodium borohydride, and sodium triethylborohydride, e) optionally, isolating the coordination complex formed in step d) from the reaction mixture.