A composition comprising trans-fluoro(pentafluorophenyl)bis(triethylphosphine)nickel(II) and methods for preparing same are disclosed.

This invention relates to a new composition of matter, 
transfluoro(pentafluorophenyl)bis(triethylphosphine)nickel(II). In another 
aspect this invention relates to methods of producing 
trans-fluoro(pentafluorophenyl)bis(triethylphosphine)nickel(II). 
The oxidative-addition of organic chlorides, bromides, and iodides to low 
valent transition metal complexes is an important method of synthesis in 
organometallic chemistry. The reaction is often facile with organic 
iodides and usually very difficult with organic chlorides. No examples are 
known in the prior art of such an oxidative-addition involving a 
carbon-fluorine bond. For example, the oxidative-addition of 
pentafluorochlorobenzene or pentafluorobromobenzene to 
1,5-cyclooctadienebis(triethylphosphine)-nickel(O) results in the 
formation of pentafluorophenylbis(triethylphosphine) nickel(II) chloride 
or bromide respectively. Further, as shown in Journal of Organometallic 
Chemistry, 84, 93-103 (1975), the oxidative-addition of bromobenzene and 
chlorobenzene to diethyl(dipyridyl)nickel(O) result in the corresponding 
aryl(dipyridyl)nickel(II) halide, while the oxidative-addition of 
fluorobenzene does not occur under similar reaction conditions. 
An object of the present invention is to provide a 
fluoro(pentafluorophenyl)bis(triethylphosphine)nickel(II) complex. 
Another object of the present invention is to provide methods for producing 
fluoro(pentafluorophenyl)bis(triethylphosphine)nickel(II) complex. 
Further aspects, objects, and advantages of the present invention will be 
apparent from the disclosure and the appended claims. 
In accordance with the present invention 
trans-fluoro(pentafluorophenyl)bis(triethylphosphine)nickel(II) is 
produced by reacting hexafluorobenzene and a nickel complex selected from 
the group consisting of tetrakis(triethylphosphine)nickel(O), 
ethylenebis(triethylphosphine)nickel(O), and 
(1,5-cyclooctadiene)bis(triethylphosphine)nickel(O). 
The reaction is conducted in a suitable solvent. Any solvent can be 
employed which does not prevent the formation of the desired product. The 
amount of solvent needed is generally an amount which will insure that 
reactants are in solution during the reaction. One skilled in the art 
having the benefit of this disclosure can readily vary the concentration 
of reactants in various suitable solvents to obtain different reaction 
rates and thus different yields of the product. Examples of suitable 
solvents include aliphatic hydrocarbons, aromatic hydrocarbons, ethers, 
aliphatic nitriles, aliphatic ketones, alkyl esters of aliphatic acids, 
and mixtures of any two or more thereof. Typical specific examples of 
suitable solvents include hexane, heptane, octane, benzene, toluene, 
xylenes, dioxane, diethyl ether, tetrahydrofuran, diethylene glycol 
dimethyl ether, acetonitrile, propionitrile, butyronitrile, acetone, 
methyethyl ketone, diethyl ketone, methyl acetate, ethyl acetate, methyl 
propionate, and mixtures of any two or more thereof. 
While some of the desired product may be produced at higher or lower 
temperatures generally the reaction is carried out at a temperature in the 
range of about 0.degree. C. to about 125.degree. C., preferably in the 
range of about 20.degree. C. to about 75.degree. C. Generally any pressure 
can be employed which allows the reactants to be reacted in solution. In 
general, the pressure will be in the range of about 5 to about 1000 psia, 
and atmospheric pressure is preferred. Reaction time is generally in the 
range of about 15 minutes to about 14 days, preferably in the range of 
about 30 minutes to about 8 days. It is to be noted that operation in the 
lower end of the temperature range can be expected to be associated with 
reaction periods in the upper end of the reaction time range and vice 
versa. 
In the practice of the present invention generally the molar ratio of 
hexafluorobenzene to nickel complex reactant is in the range of about 5:1 
to about 1:1, preferably about 2:1 to about 1:1. 
The hexafluorobenzene and the nickel complex reactants can be prepared 
using any suitable techniques known in the art. A preferred embodiment of 
the present invention involves utilizing the product mixture which results 
when bis(1,5-cyclooctadiene)nickel(O) and triethylphosphine are contacted 
in a suitable solvent to yield a product mixture containing 
1,5-cyclooctadienebis(triethylphosphine)nickel(O). Generally in preparing 
such a product mixture the molar ratio of the 
bis(1,5-cyclooctadiene)nickel(O) to triethylphosphine is in the range of 
about 4:1 to about 1:4, preferably about 1:2. Any temperature and pressure 
conditions can be employed which result in the production of 
1,5-cyclooctadienebis(triethylphosphine)nickel(O). Generally, temperatures 
in the range of -50.degree. C. to about 100.degree. C. are employed. 
Preferably temperatures of about 0.degree. C. to about 50.degree. C. are 
employed. In preparing this product mixture which is subsequently 
contacted with hexafluorobenzene any solvent can be employed which does 
not adversely affect the inventive process. Examples of suitable solvents 
include those set forth previously as suitable for the production of the 
trans-fluoro(pentafluorophenyl)bis(triethylphosphine)nickel(II). 
The product of this invention can be recovered by any suitable technique 
conventionally employed by those skilled in this art for recovering and 
purifying products contained in a solvent, i.e., precipitation, followed 
by filtration, or extraction; evaporation to dryness in vacuo, or 
separation of impurities by elution column chromatography followed by 
recrystallization. 
Since the product of this invention and the reactants employed are 
sensitive to oxygen and/or water to varying degrees, it is preferable that 
suitable steps be taken to minimize the interference of those materials 
with the desired result. Accordingly, it is preferable that the product of 
this invention be prepared and used under a substantially inert 
atmosphere, for example, in a recirculating dry box providing a suitable 
inert atmosphere, i.e. an argon atmosphere. 
The product of this invention being a 
halo(haloorgano)bis(triorganophosphine)nickel complex can be employed as 
an olefin dimerization catalyst in accordance with the teachings of U.S. 
Pat. Nos. 3,686,245 or 3,689,588.

The following examples are provided to further illustrate the present 
invention. 
EXAMPLE I 
A small glass container equipped with a magnetic stirring bar was placed in 
a dry box and charged with 0.38 g (2.0 mmols) of hexafluorobenzene. To 
this container was added in a dropwise fashion a cold solution (i.e., 
-40.degree. to -60.degree. C.) of 0.55 g (2.0 mmols) of 
bis(1,5-cyclooctadiene)nickel(O) and 0.48 g (4.0 mmols) of 
triethylphosphine in 5 ml of n-hexane. The reaction mixture was allowed to 
stand for seven days at 30.degree.-35.degree. C. The mixture was filtered 
to remove a brown sludge and the red-brown filtrate was cooled to 
-72.degree. C. to induce crystallization. The supernatant was syringed 
from the yellow-brown crystals which were subsequently dried on a clay 
plate to give 0.07 g (7% yield) of 
trans-fluoro(pentafluorophenyl)bis(triethylphosphine)-nickel(II) which 
melted at 60.degree.-61.5.degree. C. Structure verification was based on 
elemental analysis (see below) and an infrared spectrum which was 
comparable to the infrared spectrum of an authentic sample of 
trans-bromo(pentafluorophenyl)bis(triethylphosphine)nickel(II). IR 
(Nujol): 2920s, 1635 vw, 1605 vw, 1490 s, 1455 ms, 1445 vs, 1435 ms, 1410 
mw, 1375 mw, 1365 vw, 1345 vw, 1275 w, 1250 w, 1240 w, 1055 ms, 1040 s, 
1010 w, 955 vs, 793 m, 765 ms, 734 ms, 708 vw cm.sup.-1. 
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Elemental Analysis [based on F(C.sub.6 F.sub.5)Ni(PEt.sub.3).sub.2 ]: 
% C % H % Ni 
Calcd 44.94 6.29 12.20 
Found 44.50 6.71 12.7 
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EXAMPLE II 
A small glass vial equipped with a magnetic stirring bar was placed in a 
dry box and charged with a mixture of 0.40 g (2 mmols) of 
hexafluorobenzene and 1 ml of n-hexane. To this stirred solution at 
25.degree. C. was added in a dropwise manner a solution of 1.06 g (2.0 
mmols) of tetrakis(triethylphosphine)nickel(O) in 5 ml of hexane. The 
reaction mixture was stirred for 5 days at room temperature and on cooling 
to -72.degree. C. unreacted tetrakis(triethylphosphine)nickel(O) 
precipitated. The reaction mixture was then heated on a stirrer-hot plate 
(ca. 60.degree.-70.degree. C.) for a few hours and then concentrated in 
vacuo to a yellow-brown oily residue. The infrared spectrum of this 
residue was comparable to that of the 
trans-fluoro(pentafluorophenyl)bis(triethylphosphine)nickel(II) produced 
in Example I. Recrystallization of the above oil gave a yellow brown solid 
which exhibited essentially the same infrared spectrum as the 
aforementioned oily residue.