CA1307002C - Process for preparing metallocene complexes - Google Patents

Abstract

K -13926/+/B

Process for preparing metellocene complexes Abstract of the Disclosure The invention provides an improved process for the preparation of compounds of formula Ia (Ia), wherein R1 is a .pi.-arene, R2' is an anion of a .pi.-arene, L is a divalent to heptavalent metal or non-metal, Q is a halo-gen atom, q is an integer from 1 to 3 and m is an integer corresponding to the valency of L+q, said process comprising reacting an uncharged .pi.-complex of the formula IIIa

Description

~ 13926/+/B
130~0Z
-- 1 -- . ..

Pr~cess for pre~arinq metalloçe~e co~rl~x~
This is a divisional of our Canadian Application No. 428,306 filed July 14, 1983, now Canadian Patent No.
1,285,686, issued July 2, 1991.
The present invention relates to a process_for pre-paring metallocene complexes that can be used ~s initiators for the polymerization of cationically polymerizable orsanic material.
Different iodonium, sulfonium and diazoniu~ salts are known zs photoinitiators for cationically polymeris2ble organic materials from t]le literature (~.v. for exa~ple German Auslegeschrift 25 18 639, ~. Polym. Sci.~ Poly~er Che~istry Ed , 17, 1059 (1979), Ma'~romol. Chem., Suppl 3, 34~ (1979), German Offenle5ungssc~rift specifications 25 20 489, 28 54 011, 30 21 376, US patent specification 4 210 449 and British patent ap?lic2tion 2.046.269A).
On account of their rel2tively low 2bsorption ranOe (z~out 190 to 400 nm), these know~ photoinitiators require the use of sensitisers such as coLoured polycyclic hydrocarbons, e.g. perylen~ dy2s, aromatic amines, benzoin alkyL ethers or aLkoxyacetophenones, for curing cztionic~lly polymerisable systems under the 2ction of light.
The heat-curing ofsyste~s containing such photoiniti2tors is conve~ientLy carrie~ out in the presence of reducing a~ents suc~ as copper, tin, iron or cobalt salts, thiophenols,ascorbic acid and the like.
The preparation of iron-arene complexes by ligand-exchange reactions in the presence of a Lewis-acid catalyst has been described in Chem. Comm., 1971, 1071 and in Can.
J. Chem., 57, 933 (1979). There are used AlC13 or BF3-etherate as Lewis-acids.
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~3v~aoz . .

From J. Organomet. Chem., 8~, 207 (1975) the stereo-specific ring-protonation of bis-indenyliron and the subsequent isolation of the corresponding hexafluorophosphate salt is known.
In none of these references a suggestion is made to use these metallocene salts as initiators of the cationic polymerization~
It is the object of the p.esent invention to ?ro-vide a process for the preparation of initiators which can be used in novel curable compositions which compositions can be cured without the addition of sensitisers under the action of light and~or heat.
These curable composit~or.s comprise A) a cationically poly~erisable organic m~terial and B) at least one co~pound of the formula I

f (R ) (R-~l) ] an an [LQ ]~q (I) wherein a is 1 or 2, ~ is 1 or 2 and q is an integer from l to 3, M is the Fe2 cation, m is an integer corresponding to the valency ofL+q ,Q isa halogen atom, L
is a divalent to hep;avalent metal or non-metal, Rl is a -arene and R2 is a ~arene or the anion of a ~arene.
Possible r-arenes R and R are, in particular, aromatic groups of 6 to 24 carbon 2toms or heteroarom2tic groups of 3 to 30 carbon atoms, whish groups may be unsubstituted or mono- or polysubstituted by identical or different monovalPnt radicals such as halogen atoms, preferably ~hlorine or bromine ato,~s, or Cl-C8alkyl, Cl-C8alkoxy, cyano, Cl-C8alkylthio, C2-C6monocarboxylic acid alkyl ester, phenyl, C2-C5alka~oyl or benzoyl groups.

13~7~()2 These ~-arene groups ~ay be mononuclear, condensed polynuclear or non-condensed polynuclear systems, in w~ich la;t-mentioned systems the nuclei may be linked together direct or through bridge me.mbers s-~ch 2S -S- or -O-.
R as the anion of a 1~-arene may be an anion of a r-arene of the aforementioned kind, e.g. the indenyl anion, and, in partic~lar, the cyclopentadienyl anion, w~ich anions may also be unsubstituted or mono- or polysubstituted by idertical or different monovalent radicals such as Cl-C8alkyl, C2-C6monoc2rboxylic acid alkyl ester, cyano, C2-C5alkanoyl or benzoyl groups.
Alkyl, alkoxy, alkylthio, monocarboxylic acid alkyl ester and alkanoyl substituents may be straight chain or branched Typical alkyl, alkoxy,al~ylthio,monocarboxylicacida~l ester or alkanoyl substituents are: methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-octyl, methoxy, ethoxy, n-propoxy,isopropoxy, n-butoxy, n-hexyloxy, n-octyloxy, mPthylthio, ethylthio, n-propylthio, isopropylthio, n-butylthio, n-pentylthio and n-hexylthio, carboxylic acid methyl ester, ethyl ester, n-propyl ester, isopro?ylester, n-butyl ester and n-pentyl ester, acetyl, propionyl,butyryl, and valeroyl Alkyl, alkoxy, alkylthio and monocarboxylic acid alkyl ester groups con;aining 1 to 4 and especially 1 or 2 carbon atoms in the alkyl moieties and alkanoyl groups containing 2 or 3 c~rbon atoms are preferred. Preferred substituted ~ arenes or anions of substituted lYarenes are those containing one or two of the above-mentioned substituents, in particular chlorine or bromine atoms, methyl, et-nyl, methoxy, etho~y, cyano, carboxylic acid methyl or ethyl ester groups and ~cetyl groups.

,. , .

- ~ 3(~7~02 R and R may be identical or different r~arenes.
suitableheteroaromatic ~r-arenes are systems containing S-, N- and/or O-atoms.Hetero~romatic~-arenes containing S and/or O-atoms are preferred. Examples of suitable ~arenes are: benzene, toluene, ~ylenes, ethylbenzene, methoxy-benzene, ethoxybenzene, dimethoxybenzene, p-chlorotoluene, chlorobe~zene, bromobenzene, dichlorobenzene, acetylbenzene, trimethylbenzene, trimet'noxybenzene, naphthalene, 1,2-dihydronaphthalene, 1,2,3,4-tetrahydronaphthalene, methylnapht'nalenes,methoxy~aphtnalenes,et~oxynaphthalenes, chloronaphthalenes,bromonephthale~es,biphenyl, indene, biphenylene, fluorene, phenanthrene, anthracene, 9,10-dihydroanthracene, triphenylene, pyrene, naphthacene, coronene, thiophene, chromene, xanthene, thioxanthene, benzothiophene, naphthothiophene, thianthrene, diphenylene oxide, diphenylene sulphide, acridine and carbazole.
If a is 2, then ea_h R is preferably the anion of a ~-arene, and each ~ is an identical met21 atom.
E~a~ples of anions of substituted ~r-arenes ~r~: the anions of methyL-, ethyl-, r.-propyl- and n-butylcyclo?enta-diene, the anions of dimethylcyclopentzdiene,of cyclopentadiene carboxylic acid methyl ester and ethyl ester,and of acetylcyc~
pentadiene, propionylcyclopent~diene, cyanocyclopentadiene and be~zoylcyclopontadiene. Preferred anions are the anion of unsubstituted indenyl and especi211y the anion of unsub-stituted cyclopentadiene.
The preferred value of a is 1, 21 is benzene, toluene, xylene, methoxybenzene, chlorobenzene, p-chlorotolu-ene, naphthalene, methylnapht'nalene, chloron2phthelenD, met-noxynaphth21ene, biphenyl, indene, pyrene or diphenylene sulfide,and R2 is the anion of cy_lopentadiene, ac~tyl-cyclopenta~iene or indene, or ben~ene, toluene, xylene, trimet'nylbenzene, naphthalene or met'nylnap~thalene.

;:

130~G02 Particularly ~eferred are -omplexes of formula I, wherein 2 is 1, R is ~6-pyrene or ~L6-naQhth21ene, and R2 is the anion of '~5-cyclopentadiene, n is prefera~1y 1 or 2, especially 1, and q is prefertbly 1.
.

Exa~ples of suitable ~etals or non-me-21s L are Sb, Fe, Sn, Bi, Al, Ga, In, Ti, Zr, Sc, V, Cr, Mn and Cs;
12ntnanid-s suc~ as Ce, Pr ~nd Nd, or ~ctinides, such a, Ih, Pa, U or Np. S~it~ble r.on-m~tzls ar2 e,?eci~Ily B, P
2nd As. Preferzb~y L is P, As, B or Sb, wit~. P bein~ most preferred EY.amP1eS of com21eY. anions [LQm] q are BF4 , PF6 ' AsF6 , S~F6 , FeC14 ~ Sn~l~ , SbC16 , BiC16 . The ~st preferre~ co~plex anions _re SbF6 , ~F4 , AsF6 2nd PF6 .
The com~otnds cf formul2 I m-~J be prepare~ by methods known per se, e.g. by re~ctinO ~ compolnd of formu12 -I
~ (Rl) (R2~ a!~ q [X~ (II) with a salt of an anion lLQm] q, wherein 2, m, n, g, R , R , M and L are as defin~d fo- for.~ula I and ~X] q is an anion which differs from [LQm] q, Boh the com2ounds of formula II and the compo-unds of formula III

1(R1 )(R ~)a~ (III), wherein a and M are as defined above, Rl is a ~-arene or the anion o~ a ~r-aren~ and R2 is an anion of a ~r-arene, may be prepared by reacting identical or different ~r-arenes : , .
~ ' ' ' ' , .
; - . '.

1 3~ 7 ~ 02 `~
, . .

in t~e presence ~f a ~ewis acid with a salt of Fe~ .
Compounds of formulae 1, II and III are also ;uitable for effecting ligand exc~n~e,~y re.lctin~ said co~po-lnds in the presence o~ a ~e~is ~cid wit'n a ~-arene ~ic~ differs fro~ R and/or R and R respectively, In these cases, n is preferably 2 and most preferably 1.
Com?ounds of for~-la I w~erein L is a metal may also be o~tained by reacting ide~tical or diffe.ent 1r-arene in the prese~ce of a Le-~is acid with a suitable iron salt. ~inally, compounds of formula_I_ m2y also be converted in conventional m2nner into complexes of formula I having a different anion [LQm] ~, by means of anion exc~an3e.
In ~ preferred e.-nbo~iment, uncharged ~-c~?lexes of form~lla III, e.g ferrocene or bis~ -indenyl) iron(II), are used as st2rting mate~ials, and t~ese are conver.ed by ligand exch2n~e into a co!nplex of formula II, w~ich co~plex is subsequen~ly reacted with a salt of an anion [LQm~ q. In t~is reac.ion, the co~lPx of the for~ula II
obtained as intermediate is usually not isolated.
Suitable salts of a~ions ]LQm] q are, e.g. alkali metal, alkaline earth me_al or ammonium selts. It is preferred to use alkali mota~ s~lts, most pr2ferably sodi~n ~nd potassiu~ s~lts.
Suit~ble Lewis acids for tl~e above-descrihed reac.ions are e.g. AlC13, AlBr3, BF3, SnC14 and TiC14.
It may be advantageous to perform the ligand exchange reactions by adding a reducing a~ent to the reaction mixture, e.g. aluminium -~or magnesium, or subse~uently to add a reducing agent.to tne .-reaction muxture, . . :

f~

13~7C02 -e.g. Na2S03 or ascorbic acid. Aluminium is the preferred reducing agent.
In the special embodiment according to the claimed invention c~mpounds of the formula Ia L ] [ m ] tIa)l wherein Rl, L, Q, m and q are as defined above and R is an anion of a r-arene are prepared by an improved process comprising reacting an uncharged 1l-complex of the formula IIIa ,. _ _ (R )2 Fe (IIIa) w~th a ~-arene Rl in the presence of Al and a Lewis-acid followed by treatment with an acid or a salt of an acid of the anion [LQm] ~3, in which process the improv~ment consists essentially of using TiC14 as a Lewis-acid.
The ligand exchange reactions are conveniently carried out in an inert organic solvent. Examples of suitable solvents are aliphatic or cycloaliphatic hydrocarbons such as octane, nonane, decane and cyclohexane. If desired, an excess of ~-arene may also be used as solvent.
The reaction of the com~ounds of formula II with a salt of an znion [LQm] q and the anion exchange conversion of compo-lnds of formula I 2re conv2niently conducted in an zauoous or aqueo~s-alcoholic ~e~ium, e.g. in mixtures of water and me~hanol or ethanol. The salts of the anions [LQml q are use-~ in at least stoichiometric amounts, but preferably in excess thereof.

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13(~7(:~0Z
,, Cationically polymerisable organic materials which are polymerized by the initiators prepared in the process of the invention are e.g. those of the followin~ kind: They may be used alone or as mixtures of at least two components.
I. Ethylenically unsaturated compounds which are poly~erisable by a cationic mechanism Such compounds comprise 1. Mono- and diolefins, e.g. isobutylene, butadiene, isoprene, styrene, a-methylstyrene, divinylben~enes, N-vinylpyrrolidone, N-vinylcarbazole and acrolein.
2. Vinyl ethers, e g. me~hyl vinyl ethe~, isobutyl ~inyl e-her, trime_hylolpropane trivinyl ether, ethylene glycol divinyl etner; cyclic viny' ethers, e.g. 3,4-dihydro-2-forinyl-2H-pyrane (dimeric acrolein), 3,4-dihydro-2H-pyrane-2-carboxylic acid ester of 2-hydroxynethyl-3,4-dihydro-2~-pyrane 3. Vinyl esters, e g. vinyl acetate and vinyl stearate.
II. Cationically polymerisable heterocy.lic compounds, e.g, ethylene oxide, propylene oxide, epichlorohydrin, glycidyl ethers of monohydric alcohols or phenols, e g n-butyl glycidyl ether, n-octyl glycidyl ether, pheny, glycidyl ether, cresyl glycidyl ether; glycidyl acrylate, glycidyl methacrylate, styrene oxide and cyclohexene oxide oxetanes such as 3,3-dim~thy'oxetane and 3,3_di-(c~loro-methyl)oxetane; tetrahydrofuran; dioxolanes,trioxan and 1,3,6-trioxacyclooctane; lactones such as ~-propiolactone, y-va~rolactone and ~-caprolactone; thiiranes such as ethylene sulfide and propylene sulfide; azetidines such as N-acylazetidines, e.g. N-benzoylazetidine, as well as the adducts of azetidine with diisocyanates, e.g. toluylene-2,4- and 2,6-diisocyanate and 4,4'-diaminodiphenylmethane diiso_yanate; e?oxy resins; line~r and branched polymers 1 3~ 0~
_ g _ containing glycidyl groups in the side chains,e.g. homo-and copoly~ers of polyacrylate and poly~ethacrylate glycidyl esters.
Compounds of particular importance amongst these polymerisable compounds cited above are the epoxy resins, more particularly the di- and polyepoxides and epoxide resin prepolymers of the type used for the preparation of crosslinl;ed epoxy resins. The di- and poly-epoxides may be aliphatic, cycloaliphatic or aromatic compounds. Examples of such compounds are the glycidyl ethers and ~-methylglycidyl ethers of aliphatic or cycloaliphatic diols or polyols, for e~ample those of ethylene glycol, propane-1,2-diol, propane-1,3-diol, butane-1,4-diol, diethylene glycol, polyethylene glycol, polypropylene glycol, glycerol, trimethylolpropane or 1,4-dimethylolcyclohexane or of 2,~-bis-(4-hydroxycyclohexyl)-propane and N,N bis-(2-hydroxyethyl)-aniline; the glycidyl ethers of di-and p~lyphenols, for example of resorcinol, 4,4'-di-hydroxydiphenylmethane, 4,4'-dihydroxydi?henyl-2,2-propane, novolacs and 1,1,2,2-tetrakis-(4-hydroxyphenyl)ethane.
Further examples are ~-glycidyl compounds, for exa~ple ~he digylcidyl compounds of ethyleneurea, 1,3-propyLeneurea or 5-dimetnylhydantoin or of 4,4'-methylene-5,5'-tetramethyL-dihydantoin, or such as triglycidyl isocyanurate.
Further glycidyl compounds of techniral importance are the glycidyl esters of carboxylic acids, in particular of di- and polycar~oxy'ic acids Ex~?les are the glycidyl esters o succinir acid, adipic acid, azelaic acid, sebacic acid, phthalic acid, terephthalic acid, tetra- and hexahydrophthalic acid, isophthalic acid or trimellitic acid, or of dimerised fatty acids.

F ~
I

13(~02 Exarnples of polyepoxides w~ich are not glycidyl compounds are the diepoxides of vinylcyclohexane, dicyclo?en~adiene, 3-(3',4'-epoxycyclohexyl)-8,9-epo:~y-2,4-dioxaspiro[5.5]undecane, 3,4-epoxycyclohexanecarboxylic acid of 3',4'-e?oxycyclohexylmethyl ester, butadiene diepoxide or isoprene diepoxide, epoxidised linoleic acid derivatives or epoxidised polybutadiene.
Preferred epoxy resins are diglycidyl ethers, which may have been advanced, of divalent phenols or of divalent aliphatic clcohols containing 2 to 4 carbon atoms. Particularly preferred are the diglycidyl ethers, which may have been advanced, of ~,2-bis-('l-hydroxyphenyl)-propane and bis-(~-hydroxyphenyl)-methane.
Further cationically ~olyinerisable compounds which may be used are:
III. ~letnylol compolnds:
1, Aminoplasts such as the N-hydroxyn~thyl, N-methoxymethyl, N-n-butoxymethy' and N-acetoxy;nPthyl derivatives of amides or ænide type con2ounds, e.g. cyclic ùreas such as ethyleneurea (imidazolidin-2-one), hydantoin, uron (tetrahydro-oxadiazin-4-one), l,2-propyleneurea (4-methylimidazolidin-2-one), l,3-propyleneurea (hex~hydro-2H-pyrimLd-2-one), hydroxypropylene~rea (5-hydroxyhexahydro-2H-pyrimid-2-one), 1,3,5-melanine and further polytriazines s~ch as acPtoguanamine, benzoguanamine and adipoguananine.
If desired, a~inoplasts containing both N-hydroxy-methyl and N-alkoxy~ethyl, or N-hydrox~nethyl and N-a-etoxy~ethyl, grou?s m~y be use~ (for exa:nple, a hexamethylolmela~ine in w~ich l to 3 of the hy~roxyl groups have been etherified with m-thy. grou?s).

.

13(~7C02 The preferred a~inoplasts are condensation products of ~rea, uron, hydantoin, or melamine with for~nalde~de, 2nd p~r,ially or fully etnerified products of such condensstion products with an aliph2tic monohydric alcohol o~ 1 to 4 carbon 2toms.
2. Phenoplasts.
The preferred ~henopl2sts are resols made from a phenol and an _ldehyde. Su~ able phenols include phenol itself, resorcinol, 2,2-bis(p-hydroxyphenyl)propane, p-chlorophenol, a phenol substituted by one or two alkyl groups e~ch of 1 to 9 cArbon _toms, suc~ as o-, m-, and p-cresol, the xylenols, p-tertiary butylphenol, and p-nonylphenol, and also phenyl-substitu-ed phenols, especi211y p-phDnylphenol. The aldehyde -~hich is condensed with the phenol is preferably for~zldehyde, b~- other aldehydes such as acetaldehy~e and furfur21dehyde may also be ~sed. If desired, a ~ixture of such curable phenol-aldehy~e resins may be u,ed The preferre~ resols 2re condensation products of phenol, p-chlorophenol, resorcinol, or o-, m-, or p-cresol with form~ldehyde.
The curable compositions containing the initiators prepared in this invention may be obtained in any form, e.g.
as homogeneous liquid mixtures or in homogeneous or inhom~geneous glassy form Homogeneols glassy products may be prepared in a manner known pe se e.g. by liquifying soli~ poly~eris~le organic mater~ls, optionally with the addition of suit~ble solvents in the dark or under red light, by heating them to temperatures above their glass transition te~peratures, 2dding the initiator of the for~ula I, and cooling the resultant mixtures. If desired, the glassy products so obtained may subsequently be comminuted Inhomogene~us glassy products may be obt~ined e.g. by mixing glassy p~lymeris2ble mAterials in powder form with initiators prepared from the process or this invention.

~3~7C~2 The curable composition3 obtained from the initiators prepared from the process of the invention are storage stable for a consi~erable t~e at room temperature in relative darXness, e.g. in red light Depending on their composition and intended end use, e.g. for ma~ing coatings or films, they ~y be heat-cured direct. The te~peratures for direct heat-curing are prefer~bly close to the melting tem2!2rature of the initiator employed. The heat-curing is normally co~plete after about 3 to 10 minutes.
Par,icul2rly prefe-red is two-stage polymeris~tion (curing), by first activating the initiator of the forr,.ula I by irradiating t~e cura~le com2ositions and subse~uently heat-curing the activated precursors so obtained, the irrzdiation te~pe_ature being below the tem?erature zmploy2d for t'ne subsequent heat-curin~. These activ2ted precursors may n~rmally be cured ~t temperatures which are substantially lower than those required for the direct hezt-curing, with advantage in the range from 50 to 110C. Ihis t~o-stage c~ring also makes it possible to ~3C~7~Z

conerol the polym~risation in -~ particularly sim2le and advan~ageous manner. In ad~ition, activated precursor~ ob~nab~ from glassy curable co~positions Containing the initiators prepared in the process of this invention are storage s~ble for a considerable time at room te~perature even under li~'nt conditions, in contrast to known cationically poly~erisable c~mp~sitions of the prior art, e.g. those whi.h contain sulfonium or iodoni~n salts 25 initiators. This feature constitutes a further substantial advantage of the two-stage curinO and of these activate~ precursors. Activate~ precursors obtainabLe from li~uid curable compositions containing the initiators prepared in the process of the invention are aenerally of only limited storage stability under light conditions and are advantageously further used direct.
The irradiation of the cur2ble mixtures to produce the activGted precursors is conveniently effected witn an electr~n beam or with a^tinic light, pref~rably havin~ a wavelength of 2~ to 600 nm and a strength of 150 to 5000 watts. Suitable light s~urces are e.g. xen~n lamps, 2rgon la~?s, tungsten lamps, carbon arcs, metal halide and metal arc lamps such as mercury lo~ 2ressure, medium pressure and high pre;sure lamps. It is preferred to carry out the irradiation with metal halide or m~rcury high pressure lamps. The irradiation time depends on different factors, in-~uding e.g. the polymerisable organic material, the nature of the light source snd its distan^e from the irradiated material Tne irradiation time is advanta~eously from 10 to 60 seconds.
Heating of the exposed compositions may occur in conventional convection ovens. When a short time for heating up or short reaction times are required, heating may be effected by exposure with for example IR-radiation, IR-lasers or micro wave equipment .

^-`" 13~ 02 The cureble co~sition~ and the activated pre--.rsors cbtaina~Le therefro~ may also contain further additives know~ and conventi~nally employed in the technology ~f p~o~op~lymerisable ~terials. Exa~ples of such additives 2re pigmen~s, dyes, fillers and reinforcing agents, glass fibres and o~her fibrea, flame retard2nts, antistats, levelling agents, antio~idlnts and light stabilisers For increasing the storage Jtability in the dark-ness, the curable compositions and the activated precursors may contain weak organic bases like nitriles, amides, lactones or urea dèrivatives. To avoid a premature reaction because of unintended exposure, UV-absorbers and/or organic dyes may be added in small amounts.
The curable composition and the activated precursors may additionally contain mono- or polyfunctional compounds or resins which are cured by a radical mechanism-. Examples are acrylate and/or methacrylate esters of aliphatic poly-ols. The curing reaction of these substances is initiated by radical forming (photo)initiators or electron beams.
Initiators, which are activated by heat, are for example peroxides or azo compounds. Initiators activated by exposure are for example acetophenones, acylphosphineoxides or aro-matic ketones. To improve the end properties of the epoxide resins, polyfunctional hydroxy compounZs for example as described in DE-OS 2 639 395 mzy be incorporated.
A substantial advantages of the curable compositions containing the initiators prepared in the process of the present invention and of the activated precursors obtainable from said compositions is that, even when using brief curing times, the use of conventional photosensitisers may be dispensed with.

~ 1307C02 These curable compositions and the activated precursors obtainable there~rom are suitable e.g.
for the production of surface coatin~s on differe~t substrates. For this utility they are preferably e~?loyed in liquid form. Examples of suitable substrates are metals such as steel, alu~inium, copper, cadmium and zinc, ceramics, glass, plastics, paper or wood If in the two-stage polymerisation described above initially only a part of the coating is irradiated through a maslc, then the areas w~ich have not been exposed may be re~oved with a suitable solvent after a subsequent brief heat-curing. These curable compositions are therefore suitable for image re?roduction or for the production o~ printing plates and, in particular, of printed clrcuits (photo-resists) by methods w~ic~ are ~now~ per se (q.v. for example ~ritish patent specifieation 1 495 746).
The curable compositions and the activated precursors obtainable therefrom may also be used as adhesives or for making putties, fillers or fibre-reinforced composites and làminates. Further, it is possible to c~re the curable co~positions which contain an epoxy resin or a phe~oplast as poly~erisable material, in two stages.
The procedure is that the mixture of initi2tor of the formula 1 and epoxy resin or phenopl~st is first converted into the partially cured B-stage by irradiation in the prese~c2 ~f a late~t, heat-activated crosslin~ing age~t for the epoxy resin or p~enoplast The partially cured composition 80 obtained is then heated in a second stage so th~t curing is completed. It is preferred to use a polycarboxy'ic anhydride as latent, heat-activated crosslinlcing sgent.
The curable c~mpositions containing the initiators prepared in the process of this invention which contain epoxy resins or phenoplasts are suitable in particular for making printed cir-cuits, ilament windinss, mouldins :
...... .

'' ~ 30 7 C, 0 2 compositions or adhesive films (q.v. for example published European patent ap?lication 44274, w~erein such kno~n utilities are describe~ in detail), For the above utilities, the curable compositions or the activated precursors obtainable therefrom, conveniently contain O.l to 15 % by weight, preferably ~.5 to 5 % by weight, based on the ~olymerisable organic mate.ial A), of at least one compound of the formula I.
Of particular interest also are homogeneous, glassy, curable compositions and activated precursors obtainable : therefrom,which c~ntain up to equimolar am~unts of an initiator of the formula I and a polymerisable organic material A), in which connection "equimolar"will be under-8tood tomean the reactive group of the polymerisable organic material.Such mixtures may be used as hardeners for cationically polyme isable m~terials of the kind specified above, in particular epoxy resins. Non-activated curable mixtures of this type are advantegeously added direct to glassy cationically polymerisable materials end heat-cured in the aforeDentioned m~nner. Correspondin~
activated precursors are suitable as hardeners for cationic~lly poly~erisa~le material,in li~uid or solid i i (glassy) form.

SDl7 13Q7~ 02 SUPPLEMENTARY DISCLOSURE
The invention as described in the Principal Disclosure hereinabove, and also as described and claimed in our Canadian Patent No. 1,285,686, dated July 2, 1991, of which the present application is a divisional, provides activated curable compositions obtainable by irradiating a curable composition which comprises A) a cationically polymerisable organic material and B) at least one compound of the formula I
[Rl) tR2M)a~ +an an [LQ ]~q (I) q wherein a is 1 or 2, each of n and q independently of the other is an integer from 1 to 3, M is the cation of a monovalent to trivalent metal of groups IVb to VIIb, VIII or IB of the Periodic Table, m is an integer corresponding to the valency of L + q, Q is a halogen atom, L is a divalent to heptavalent metal or non-metal, Rl is a ~ -arene and R2 is a ~-arene or the anion of a ~-arene, at a temperature which is below that employed forthe subsequent heat curing. These compositions are suitable for the production of surface coatings, printing plates and in particular, printed circuits. The curable compositions comprising (A) and (B) as defined above may be heat-cured direct, but are preferably first irradiated to give storage-stable activated precursors and then heat-cured.
As pointed out previously herein in page 5 of the Principal Disclosure, the compounds of Formula I may be prepared from compounds of Formula II; and the compounds of Formula II and Formula III:
[(Rl )(R2M)a (III) wherein a and M are as defined above, R1 is a~-arene or the anion of a ~-arene and R2 i8 the anion of a ~-arene, may be prepared by reacting identical or different ~ -arenes in the presence of a Lewis acid with a salt of Fe2+; and compounds of Formula I wherein L is a metal may also be obtained by reacting identical or different ~-.F~
~A

.

~3()~Ç ~
SDl8 arenes in the presence of a Lewis acid with a suitableiron salt.
Also, as previously disclosed her~in in the Principal Disclosure, suitable Lewis acids for such reactions are AlC13, AlBr3, BF3, SnCl4 and TiCl~.
Further, as previously disclosed hereinabove in the Principal Disclosure~ in a special embodiment of the present invention compounds of the formula Ia [ R Fe R ~3[ LQm ] . (Ia), wherein R1, L, Q, m and q are as defined above and R2 is an anion of a~ -arene are prepared by an improved process comprising reacting an uncharged ~-complex of the formula IIIa [ 2' ~ (IIIa) with a ~ -arene R1 in the presence of aluminum and a Lewis-acid followed by treatment with an acid or a salt of an acid of the anion [LQm]~9, in which process the improvement consists essentially of using TiCl4 as the Lewis-acid.
It has been found that when using TiCl4 as a catalyst in the ligand-exchange reaction considerably higher yields of reaction products are obtained as compared to the analogous reaction wherein AlC13 is used as the Lewis acid.
The following three examples are now presented to illustrate the present invention as claimed herein.
These examples demonstrate that the process of the present invention brings about reaction yields which are twice as high (or even higher) as those achieved if ~ ' , 13(~ 02 TiC13 were used instead of TiC14 as the Lewis acid.
Examples 1 to 3:
0.1 moles ferrocene, 0.1 moles aromatic compound and 0.1 moles Al-powder are stirred at 60C in 100 ml octane-fraction until all of the ferrocene is dissolved. Then 0.2 moles of the corresponding Lewis-acid are added under stirring. The reaction mixture is heated up to 110C and is stirred for 5 hours at this temperature.
The warm reaction mixture is poured onto 500 g ice containing 10 ml Co~c~hydrochloric acid and is stirred for 30 minutes.
After filtratlon and phase separation a concentrated solution of an acid or of an salt thereof ~e.g. RPF6 or HPF6) is dropped lnto the resulting mixture. The precipitating solid is separated by filtration, washed with water and dried at 40C (under vacuum; 13 mN/m2). The results are given in the following table:
Example complex A1Cl~- TiCl~-No, cata yst cata yst % react i~yi~l CP3 \ / Fe ~ PF6 ¦ 40 ~ ¦ 75,3 2 ~ /CF-~ Fe~ ~ pi FF6~ ~ 201) 63,8 SD20 13~7~ C)2 1) comp. C.R. Acad.Sc. Paris, Ser. C. 272, 1337 (1971) 2) comp. Can.J.Chem., 57, 933 (1979) 3) Py is a mixture of pyrene and partially hydrogenated pyrenes (as discussed in Can.J.Chem., 57, 933); H-NMR
1nvestigation of the products demonstrates that a lower quantity of partially hydrogenated pyrenes is formed in the TiC14 process as compared with the AlC13 process~

~;~
.

Claims

What is claimed is :

1. An improved process for the prepara-tion of compounds of formula Ia (Ia), wherein R1 is a .pi.-arene, R2' is an anion or a .pi.-arene, L is a divalent to heptavalent metal or non-metal Q is 2 halo-gen atom, q is an integer from 1 to 3 and m is an integer corresponding to the valency of L+q, said process comprising reacting an uncharged .pi.-complex of the formula IIIa (IIIa) with a .pi.-arene R1 in the presence or Al and a Lewis-acid followed by treatment with an acid or a salt of an acid of the anion [LQm]q-, in which process the improvement consists essentially of using TiCl4 as a Lewis-acid.