US 3773632 A
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United States Patent; [191 Lehmkuhl ELECTROCHEMICAL PRODUCTION OF TRANSITION METAL ORGANOMETALLIC COMPLEXES  Inventor: Herbert Lehmkuhl,Mulheim/Ruhr,
Germany  Assignee: Studiengesellschaft Kohle mbII,
Mulheim, Germany  Filed: Feb. 11, 9171  Appl. No.: 114,723
 Foreign Application Priority Data 845,074 8/1960 Great Britain 204/59 .Nov. 20, 1973 Primary Examiner-F. C. Edmundson Attorney-Burgess, Dinklage & Sprung [5 7 ABSTRACT Organometallic complexes of transition metals, free of carbon monoxid are produced electrochemically by electrolysis in a cell having two metal electrodes and electrolyte solution comprising an organic solvent, a suitable complexing agent and, optionally, a conducting salt. The transition metal compounds involved comprise those of Groups IVb to VIIb and VIII and they may be used in metallic form as the anode. The cathode is advantageously a metal toward which the electrolyte is inert, e.g. aluminum. The complexing agent preferably comprises a compound of a transition metal of Group IVb, VIb or VIII, e.g. an acetylacetonate, organic acid salt or alkanolate of titanium, chromium, iron, cobalt or nickel. Quaternary ammonium or alkali metal salts may be used as conductors.
The products are suited for catalysis of hydrogenation, oligomerization and isomerization.
13 Claims, No Drawings ELECTROCHEMICAL PRODUCTION OF TRANSITION METAL ORGANOMETALLIC COMPLEXES The present invention relates to the electrochemical production of organometallic complexes of transition 5 metals, free of carbon monoxid Organometallic compounds are by definition those compounds in which the metal is bound to a C atom or to a C-C multiple bond either through a 8 bond or through a 1r bond (see, for example, 1.1. Eisch, The 10 Chemistry of Organometallic Compounds," The Macmillan Company, New York, 1967, p.l).
Organometallic complex compounds of the transition:
metals are of great technical interest since in many cases they are active catalysts for the hydrogenation of unsaturated organic compounds, for the oligomerization of 1,3-diolefins, for the codimerization of olefins or alkynes with l,3-diolefins (cf. G. Wilkeandcollaborators, Liebigs Ann. Chem. 727, 143-207 (1969) or,
for example, for the isomerizat-ion of olefins or the 2.01
oligomerization of alkynes.
According to German Patent 1,191,375- such transition metal complex compounds can be preparedbythe reduction of transition metal compounds by means of metal alkyl, cycloalkyl, aryl oraralkyl: compounds ofi Groups I to ill metals in the presence of organic complexing compounds. Electronv donors whichcontain C-C multiple bonds or atom groupings with non bonding electron'pairs are the complex-ing agents, ex-
amples being alkyl and'arylcompounds of the elements of the Group Va ofthe Periodic System. The organic compounds of metals ofGroups l, llandlll used asreducing agents are all extremely sensitive to air and moisture, and they often ignite upon the access-of air or oxygen or react explosively. with=water or alcohols; 3
Handling them therefore requires special'precautions (cf. Houben-Weyl, Praeparative Methodender Organischen-Chemie, Vol. XIII/4, Organische Verbindungen des Aluminiums, p. 19).
it is an object of the present invention'to provide a 40 process for producing organometallic complexes of transition metals which do not require the use of organometallic compounds of Groups litolll as reducing. agents.
This and other objects and advantages are realized in 4 accordance with the present invention, whereinorganometallic coordination compounds of thetransition i metals are very easily obtained by anelectrochemicali reaction in the presence of appropriate complexing agents. in the process of'the invention, an electrolyte solution is electrolyzed in an electrolysis cell betweentwo metal electrodes, the said solution consistingof a compound of a transition metal in the usual oxidation state an appropriate organic solvent, optionallya conductive salt such as an alkali 'metalor=tetraalkylammonium halide, and a suitable complexingaagent,
It is extremelysurprising that no metal deposition-occurs at the cathodeduring-the electrochemical reduction of the transition metal compounds under these conditions. Such metal deposition occurs immediatelyif the same electrolyte, e.g. one consisting-of'nickel' acetylacetonate, tetrabutyl-ammonium bromide and tetrahydrofurane as solvent, is electrolyzed in: th'ezabsence of a complexingagent. lt'isfurthermore known that the transition metalslused accordingzto the invention do not react with the complexingagents of them-- vention when they arein elemental form,- e.g.', in the reduced at the cathode to the zero valence state and,
before the zero-valence metal combines with other atoms to form a crystal lattice and hence larger aggregates, reacts with the complexing agent present in the electrolyte to form the organometallic complex.
The electrochemical reduction of coordination compounds of the transition metals to complexes of lower valence states is known from the technical literature. For example, success has been achieved in the electrochemical reduction of cations complexed to 2,2- bipyridyl in a series of steps through a plurality of valence states down to zero valence state; see, for example, S. Her-20g and R. Taube, Z. Chem. 2, 208 (1962'). Also, the reduction of metal ions complexed to tertiary phosphines has been described through the example of the reduction of [(Ph)';,P]},-RhCl' in tetrakistriphen-ylphosphinerhodi'umw') (D'.C. Olson and W. Kei'm', Inorg. Chem. 8; 2028 (1969)). A description has also been given of the electrochemical reduction of an orgeneral chemical reaction; this can be expressedas follows: r
M Transition metal [1 Complexingligand n:= Valence-state of the transition metal pe Number of-electrons q.='-chan'ge in'the coordination number In the case of organometallic complex compounds,
' thisemeansthatthe organometallic compound must a] ready be present'and the metal then is reduced from a higher to a lowervalence.
An electrolytic processfor the preparation of organic transition metal compounds with cyclopentadienyl radicals or substituted cyclopentadienyl radicals is disclosed-in the technical'literaure. In this process, accordingto U. S. Pat: No. 2,960,450, for example, or at:- cording-to publicationby S. Valcher and E. Alumni, Ric. Sci. 38, No. 6,527 (1968), by electrochemical methods" a cyclopentadienyl radical that is already bound to metal is transmetallized from that metal to another; an example is the electrolysis of a solution of sodiumor thalliumcyclopentadienyl using an anode of iron,- nickel or manganese, according to the following reaction:
2 m Op Fe (Ni; Mn) FeCpz (or NiCp; or
MnCpz, as the case may be) --m formiin'which-it: is bound toanauxiliary metal, as alkali metal 'cy'clopentadienyhfor example, and all that the electrolysis does isbring-about a transmetallization of the radicalz 'Th'e same isthe case even when, according to a variant process described in U. S. Pat. No. 2,960,450, the alkali metal cyclopentadienyl compound is constantly being formed in the electrolysis cell by the reaction of the cathodically separated alkali metal with cyclopentadiene.
In the process of the present invention, transition metal compounds of higher valence state are reduced in the presence of compounds which do not function as complexing agents in relation to the metal in this valence state. Nevertheless, the cathodic separation of metal does not takeplace, and the complex compounds formed with the metal are obtained in the lower or zero valence state in good yields. This establishes that the organometallic compound is first formed by the reaction of the invention.
With suitable complexing agents, the reaction of the invention can also be used for the preparation of zerovalence or low-valence coordination compounds of the transition metals with alkyl, aryl, alkyloxy or aryloxy compounds of trivalent phosphorus, arsenic or antimony. These are electron donors which have a nonbinding pair of electrons. An example is the preparation of tetrakis-[triphenylphosphine]-nickel() Ni[C H from a bivalent nickel compound which is not complexed with triphenylphosphine. Another example is the preparation in like manner of tetrakis- [triphenylphosphite]-nickel(0) Ni[(C H O) P] Compounds of the transition metals of the fourth to seventh sub-group and of the eighth group of the Periodic System (lVb, Vb, Vlb, Vllb, Vlll) are used as transition metal compounds, examples being titanium, zirconium, vanadium, chromium, molybdenum, manganese, iron, cobalt, nickel, palladium and platinum, preferably the metals ofGroup VllI, Vlb and Nb, especially nickel, cobalt, iron, chromium and titanium.
It is desirable to use for the electrolysis those compounds of the transition metals which are soluble in the solvents used. Such compounds are the metal acetylacetonates, salts of organic acids or salts with other organic radicals, e.g., alkanolate radicals or complex alkanolate radicals such as [Al(OC H Often the an hydrous halides of the transition metals can be used, either by themselves or in the form of complex compounds with Lewis bases, e.g., TiCl TiCl '3 THF, FeCl or CrCl 3 THF (THF tetrahydrofurane).
The complexing agents for the coordination compounds to be prepared according to the invention are electron donors containing CC multiple bonds or atom groups with non-bonding electron pairs. The following are especially suitable:
1. Cyclic polyolefins such as cyclooctadiene-(1,5), cyclooctatetranene, cyclododecatriene-( 1,5,9); cyclic monoolefins with strained double bonds or l,3-diolefins or alkynes.
2. In the class of electron donors with non-bonding electron pairs, the alkyl and aryl compounds of elements of Group Va of the Periodic System with an atomic number of at least 15, examples being tertiary phosphines, arsines, stibines and phosphites.
Suitable solvents are aromatic hydrocarbons such as benzene and toluene; aliphatic or cycloaliphatic monovalent or polyvalent ethers such as diethyl ether, tetrahydrofurane, dimethoxyethane or 2,2-dimethoxydiethylether or other dialkyl ethers of ethylene glycol or of dior triethylene glycol; cyclic l,2-propylene carbonate; and especially pyridine, have proven desirable for the process of the invention.
Since the transition metal compounds have extremely little if any conductivity in the preferred solvents, it is advantageous to add difficultly reducible salts which dissociate into ions to serve as conductors, especially tetraalkylammonium halides or ammonium compounds with other acids as well as lithium halides. The cathodes can be made of any metals that are inert with respect to the electrolyte, e.g., Al, Hg, Pb, Sn, graphite, iron, platinum, nickel, titanium, etc. It is advantageous to use as anodes those metals whose complex compounds are to be prepared; in this manner the preparation of the organometallic complex compound from the metal (used as the anode) and the complexing agent can be performed by electrochemical methods as an overall reaction for the electrolysis process. The metal then dissolves in proportion to the current applied. In many cases the use of an aluminum anode has proven especially desirable.
The preparation of the transition metal complex compounds is performed in the following manner: solutions or suspensions of compounds of the transition metals in an appropriate solvent, with the addition of a conducting salt if necessary, are electrolyzed between two metal electrodes which are best located at a very short distance from one another of about 0.2 to 5 cm, at temperatures between -40 and +lOOC, preferably 20 and +50C. After the calculated amount of current has flowed through the cell, the complex com-- pound can be isolated from the reaction mixture. If the resulting transition metal complex compounds are to be used as catalysts, however, the catalytic reaction can be performed in the electrolysis cell itself during the electrolysis by the addition of the components that are to be transformed by the catalyst.
By way of example, the following transition metal complex compounds can be prepared by the process of the invention:
cyclooctatetraenetitanium chloride [CsHsTlCilg from titanium tetrachloride ariazyldbcia'tetiieaea all-trans-cyclododecatriene-( 1 ,5,9 )-nickel(0)-triphenylphosphine(C l-l, )Ni'P(C,l-l from nickel acetylacetonate, cyclododecatriene-(1,5,9) and triphenylphosphine;
all-trans-cyclododecatriene-( l ,5,9)-nickel(0) [(C H )Ni] from nickel acetylacetonate and cyclododecatriene-(l,5,9); bis-[cyclooctadiene-( l,5)]-nickel(0) [(C H,,),Ni]
from nickel acetylacetonate and cyclooctadienefrom nickel acetylacetonate and cyclooctatetracne, and the cyclooctatetraene metals of the elements iron, cobalt, chromium, molybdenum, tungsten, zirconium, etc. The following can additionally be prepared according to the invention:
Cobalt-containing catalyst solutions, by the electrolysis of cobalt acetylacetonate or cobalt-bis-[tetraethoxyaluminum] in THF. This solution can transform butadiene to 5-methylheptatriene or transform diphenylacetylene to hexaphenylbenzene.
Furthermore, by the process of the invention there can be obtained catalyst solutions containing nickel which transform butadiene to cyclododecatriene- (l,5,9) or to cyclooctadiene and vinylcyclohexene. In the electrolysis of iron (Ill) chloride in THF, catalyst solutions are formed which transform butene-(Z) to hexamethylbenzene.
The CO-free organometallic complex compounds of transition metals obtained by the process of the invention, or their solutions, can be used as catalysts for the oligomerization of olefins and diolefins.
The invention will be further described in the following illustrative examples which were carried out with the exclusion of air and moisture.
EXAMPLE 1 A solution of 12 g 45.6 mmoles of nickel (ll) acetyl acetonate and 5 g of tetrabutylammonium bromide in 100 ml of THF is saturated with butadiene and electrolyzed at about 20C between two aluminum electrodes each having an effective electrode surface of 20 cm and spaced 3 cm apart. Current: 30 mA, 60 V. After the passage of 46.5 m faradays, butadiene is introduced into the electrolysis cell at 20C. After the passage of a total of 100 m faradays the solution is vacuumdistilled, finally at 60Cand 0.001 mm Hg, passing all volatile substances into a chilled condenser. 1n the fractionation that followed, there was obtained 21.5 g of a mixture of the following cyclododecatriene-( 1,5,9) isomers, boiling at 100 to ll0/l5 mm Hg:
EXAMPLE 2 A solution of 7.0 g (27.3 mmoles) of nickel (ll) acetylacetonate, 28.6 g (109 mmoles) of triphenylphosphine and 2 g of tetrabutylammonium bromide in 50 ml of THF is electrolyzed at 40C between two aluminum electrodes. Current: 60 V, 40 mA, at 3 cm electrode spacing; amount of current applied: 55 m faradays. A dark brown solution results, from which reddish brown, glittering crystals precipitate. After filtering, washing with absolute methanol and drying, 25 g of nickel tetrakistriphenylphosphine is obtained. Yield: 83% of theory.
EXAMPLE 3 Twelve g (46.5 mmoles) of nickel (ll) acetylacetonate and 2.5 g of tetrabutylammonium bromide are dissolved in 100 g of pyridine. After the addition of g (92.5 mmoles) of cyclooctadiene-( 1,5) the solution was electrolyzed at 0 C between two aluminum electrodes. Current: 30 mA, 20 cm per electrode surface; 18 volts. During the electrolysis the color of the electrolyte changes from blue green to brownish yellow. After the passage of half of the amount of current required, lemon-yellow crystals begin to precipitate from the solution, and after a total of 2,000 mA x hours they are filtered out at 0C, washed with a benzene-ether solution (4:1) and dried. The crude product is approximately 96% pure. Yield: 7.9 g, corresponding to 70% of theory.
Weight loss of the aluminum anode: 0.72 g, corresponding to 100% of theory.
After the addition of a fresh quantity of nickel acetylacetonate the electrolyte can be used for another electrolysis.
EXAMPLE 4 10.2 g (40 mmoles) of nickel (ll) acetylacetonate, 3 g of tetrabutylammonium bromide and 16 g (154 mmoles) of cyclooctatetraene are dissolved in 1 16 g of pyridine and electrolyzed at 20C between two aluminum electrodes. The electrolyte changes color from blue to dark red. After about 20% of the required amount of current has passed, darkly glittering crystals of cyclooctatetraene-nickel precipitate. After a total of 1,770 mA.h, the crystals are filtered at 20C and washed with benzene. Yield: 3.4 g, corresponding to 63% of theory. After concentration of the mother liquor, another 1.7 g can be isolated. Total yield: 5.1 g, corresponding to 93% of theory.
in a procedure analogous to Example 4, using tet rahydrofurane as the solvent, bis-[cyclooctatetraene]- iron(0) was obtained from iron (lll)-acetylacetonate, and tris [cyclooctatetraene]-dichromium was obtained from chromium (Ill) acetylacetonate.
EXAMPLE 5 Ten g (39 mmoles) of cobalt (ID-acetylacetonate and 6 g of tetrabutylammonium bromide are dissolved in 100 ml of THF. After saturating the solution with butadiene, it is electrolyzed between two aluminum electrodes with 50 to 30 mA and 25 volts. After m faradays have been passed, the solution is freed of the THF in vacuo at 0.02 mm Hg. The residue is dissolved in benzene. This catalyst solution transforms butadiene at 20C into 5-methylheptatriene-( 1,3,6) and noctatriene.
EXAMPLE 6 Butadiene is introduced into a solution of 4.7 g (10 mmoles) of Co[Al(OC H and 5 g of tetrabutylammonium bromide in 60 ml of dimethoxyethane during the electrolysis. After the passage of 535 mA.h, the catalyst solution is fractionally distilled, yielding 22 g of 5 -methylheptatriene-( 1,3,6).
EXAMPLE 7 6.3 (33 mmoles) of titanium (IV) chloride and 6.9 g (67.5 mmoles) of cyclooctatetraene are dissolved in 70 ml of THF and electrolyzed at 40C between two titanium electrodes. Current: 10 mA, 60 volts. A dark solution develops, out of which dark green crystals precipitate. Amount of [C H TiCl] 6.3 g( 17 mmoles) of the dimeric compound. Molecular weight determined by mass spectrometry: 374.
EXAMPLE 8 A solution of 10.4 g (40.4 mmoles) of nickel (ll) acetylacetonate and 1.9 g of tetrabutylammonium bromide in ml of pyridine is electrolyzed between two aluminum electrodes after the electrolytes have first been saturated at 20C and then kept constantly saturated by a moderate infeed of butadiene during the electrolysis.
After the passage of 2,5 80 mA.h, a weight loss from the aluminum anode of 0.868 g can be determined, corre sponding to of theory. The current conditions are 14 to 23 volts and 0.3 A per square decimeter of electrode area. After the end of the electrolysis the reaction mixture is fractionally distilled in vacuo. 23 g of cycloododecatriene-(l,5,9) is obtained, of which 9305% consists of the trans,trans,trans compound, 6.9% of the trans, trans,cis compound and 0.3% of the trans,cis,cis compound.
EXAMPLE 9 The procedure is the same as in Example 8, but 80 The liquid reaction product is difficultly soluble in the propylene carbonate and separates as a second phase above the propylene carbonate phase, or it can be extracted with pentane or another hydrocarbon.
Mixtures of cis-trans isomers of cyclododecatriene- (1,5,9) are obtained:
trans,trans,cis: 13% trans,cis,cis: 3%
EXAMPLE 10 A solution of 7.9 g (30.8. mmoles)of nickel (ll) acetylacetonate, 32.9 g (185 mmoles) of diphenylacetylene and l.6 g of tetrabutylammonium bromide in 80 ml of THF are electrolyzedat 40C between two aluminum electrodes. Current: 45 volts, 0.4 A/dm During the electrolysis the initially green solution turns brown. After the passage of 1,950 mA.hours, 0.45 g of aluminum has dissolved from the anode, corresponding to 68% of theory. 50 ml of diethyl ether is added to the solution and the solution is filtered. After the precipitate has been dried, 20 g of hexaphenylbenzene (melting points 430C) is obtained, i.e., 61% of theory. The infrared spectrum confirms the structure of hexaphenylbenzene.
EXAMPLE 11 The procedure is as described in Example 4, but instead of nickel acetylacetonate, 7.9 g (22.5 mmoles) of.
iron ([11) acetylacetonate is used in 200 ml of pyridine in which 8.4 g of lithium chloride are dissolved as a conducting salt instead of the tetrabutyla mmoni urn bromide. The electrolysis is performed between two aluminum electrodes at C. Current: 30 mA 30 cm area of each electrode surface. After 61 hours of electrolysis 0.612 mg of aluminum has dissolved from the anode, corresponding to a current yield of 100%. A brown powder is obtained from the dark brown electrolyte solution after the pyridine has been removed by evaporation at 0C and 0.0001 mm Hg; it is bis-[cyclooctatetraenel-iron contaiminated bylithiurn chloride and aluminum tris-acetyl-acetonate.
EXAMPLE 12 20C. The rusty brown, powdery residue is extracted with warm benzene and thus free of conducting salt. Yield of tris-[cyclooctatetraene]-dimanganese: 1.6 g (3.8 mmoles), corresponding to 51% of theory.
EXAMPLE 13 A solution of 6 g of vanadylacetylacetonate in 80 ml of tetrahydrofurane, to which 1.5 g of tetrabutylammonium bromide has been added as conducting salt, plus 4.1 g (40 mmoles) of cyclooctatetraene, is electrolyzed between aluminum electrodes, current 30 mA at 0.20 dm of surface per electrode, 40 volts, temperature 0 to C. The anodic current yield amounts to 65%. After evaporation of the solvent, bis- [cyclooctatetraene]-vanadium is obtained, contaminated by tetrabutylammon ium bromide.
EXAMPLE 14 A solution of 2.0 g (7.8 mmoles) of cobalt (ll) acetylacetonate in ml of pyridine, in which 3.3 g of lithium chloride is dissolved as a conducting salt, along with 5 'g (46 mmoles) of cyclooctadiene-( 1,5) and 0.45 g (10 mmoles) of ethanol, is electrolyzed between two aluminum e lgc tro d es fo 20 hours at -5C and 30 mill ia'mperes 31"30 volts. 0.207 g of aluminum dissolve from the anode, corresponding to an anodic current yieldjof 100%. dark brown electrolyte solution obtained was fieedk'if ridiii5 30c .and 0.001 mm Hg. The gray, powdery residue obtained is extracted with 15 ml of pentane chilled to -20C. After the pentane extract has been chilled to --C, 0.82 g of 1r-cyclooctenylcobalt-cyclooctadiene-(1,5) precipitates from it. This corresponds to a yield of 37% of theory.
When the anode and cathode are in chambers separated by a diaphragm, e.g., by a porous cylindrical clay tube or by a glass fiber sleeve or a filter sleeve of cellulose, anodes of cobalt metal can be used instead of alu minium anodes. The anodic current yield then amounts to about 67 to 70 i In addition to the substances illustrated the transition metal compounds may be present as salts of aliphatic acids such as acetic, atearic, benzoic, chloracetic, and the like; alkanolates such as those of methanol, butanol, ethyl hexanol, propanol, tert. butanol, and the like, in addition to the illustrated ethylate; halides such as the bromide or iodide; and complexes with other Lewis bases such as triethyl phosphine, tricyclohexyl phosphine, or tri-ortho-phenyl-phenyl phosphite. Other complexing agents include isoprene. Other conducting salts include lithium bromide or iodide, tetrmethylammonium chloride, and tetrabutyl-tetraphenyl borate.
It will be appreciated that the instant specification and examples are set forth by way of illustration and not limitation and that various modifications and changes may be made without departing from the spirit and scope of the present invention.
What is claimed is:
1. Process for the electrochemical preparation of CO-free organometallic complex compounds of transi tion metals of Groups lVb to Vllb and VIII of the Periodic System, comprising electrolyzing in a cell between two inetal electrodes an electrolyte solution free of carbonyl compound 'and comprising (a) an organic solvent, (b) a compound of the transition metal selected from the group consisting of an acetylacetonate, a salt of an aliphatic acid of two to 18 carbon atoms, a salt of benzoic acid, and an alkanolate of l to 8 carbon atoms, (C) a complexing agent which is an electron donor containing C-C multiple bonds or atom groups with non-bonding electron pairs, and (D) a conducting salt selected from the group consisting of a tetrao rganoammonium and an alkali metal halide, the mixture of complexing agent and transition metal compound being reduced at the cathode and thereby forming the organometallic complex compound.
2. Process according to claim 1, wherein the conducting salt is an ammonium salt, a tetraalkylammonium halide or a lithium halide.
3. Process according to claim 1, wherein the cathode of said cell comprises at least one of aluminum, mercury, lead, tin, graphite, iron, platinum, nickel or titanium.
4. Process according to claim 1, wherein the anode of said cell comprises the transition metal whose organometallic complex is being produced.
5. Process according to claim 1, wherein the electrodes are spaced apart about 02 to 5 cm.
6. Process according to claim 1, wherein the transition metal comprises at least one of titanium, chromium, iron, cobalt and nickel.
7. Process according to claim 1, wherein the transition metal is present as an anhydrous halide.
8. Process according to claim 1, wherein the complexing agent is a cyclic polyolefin, a cyclic monoolefin with a strained double bond, a 1,3-diolefin or an alkyne.
9. Process according to claim 1, wherein the complexing agent is an alkyl or aryl compound of a Group Va element having an atomic number of at least l5.
10. Process according to claim 9, whrein the complexing agent is a tertiary phosphine, phosphite, arsine or stibine.
11. Process according to claim 1, wherein said solvent comprises an aromatic hydrocarbon, an aliphatic ether, propylene carbonate or pyridine.
12. Process according to claim 2, wherein the cathode of said cell comprises at least one of aluminum, mercury, lead, tin, graphite, iron, platinum, nickel or titanium, the anode and the transition metal whose organometallic complex is being produced comprises at least one of titanium, chromium, iron. cobalt and nickel, the complexing agent is a cyclic polyolefin, a cyclic monoolefin with a strained double bond, a 1,3- diolefin, an alkyne, a tertiary phosphine, phosphite, arsine or stibine, said solvent comprising an aromatic hydrocarbon, an aliphatic ether, propylene carbonate or pyridine, said electrodes being spaced apart a distance of about 0.2 to 5 cm and the electrolysis being performed in the substantial absence of air and moisture at a temperature of about 20 to C.
13. Process according to claim 1, including adding an olefin or alkyne to the electrolyte solution during electrolysis whereby a oligomer of said olefin or alkyne iss directly produced.
UNITED STATES PATENT OFFICE. CERTIFICATE OF CORRECTION 1 mm No; 5,775,652 Dated November 20, 1975 In ent 1-( It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:
. Page 1, 5;; 22'] egrre c date to read -'-1971--.-. Col. 2, 1inej24 correct spelling of "Fischer";
Col. 2, line 48 change "Alumni'." to -A1unni I 3 Col. 3, 11m 41 nan ".[A1(CO H to umucozus) C01. 3 line ;53, 'correct spelling of "cycloo ctatetraene";
Col. 4, line 50, after "nickel" cancel "(00) "fand substitute therefor (0) Col; 6, line- 58, cancel "93057." and substitute therefor "93.51"". .Co l. 7,;1ine 23', change "points" to "poir t:-' l
061. 7, line 40, siege "0.00.01" to 0,901.
FORM PC4050 I I I 7 I v USCOMM'DC scan-ps9 l u.s. soulful-mu rnnmue omcz: 930
Col. 7,, lines and 55, chahge "free" to freed c I Pege 2 j UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 5,775,63 Dated No r 20, 1975 I Inventor (s) Herbert Lehmkuhl It is certified that error appears in the above-identified patent and that. said Letters Patent are hereby corrected as shown below:-
0.0 8, line 28, ch nge 'v' t earic'" to --stearic- C01. 10', l inellclairni l3), change "iss" to'--is--.
Signed and sealed this 5rd day of December. 197A.
(SEAL) Attest: I
c. MARSHALL ,DANN
MCCOY M. vc11esscm JR.- Attesting Officer Commissionerfi'of Patents v uscoMM-Dc man-P U.5. GOVERNMENT PRINTING OFFICE: 0
FORM P C-1050 (10-69)