Hydrogenation of unsaturated hydrocarbons with cyclometallated transition metal catalysts

A method for hydrogenating olefins and alkynes is provided wherein the unsaturated hydrocarbon is reacted under mild conditions in the presence of a cyclometallated transition metal catalyst which shows greater resistance to degradation caused by oxidation.

BACKGROUND OF THE INVENTION 
This invention relates to the hydrogenation of unsaturated groups in the 
presence of transition metal catalysts. More particularly, this invention 
relates to the reaction of hydrogen with unsaturated hydrocarbons in the 
presence of a transition metal catalyst containing a cyclometallated group 
to provide the corresponding saturated hydrocarbon. The use of transition 
metal catalysts for olefin hydrogenation is well-known in the art as 
indicated by Kirk-Othmer in Encyclopedia of Chemical Technology, 6, 
(1978), pp. 583-584. James discusses a series of transition metal 
catalysts within Advancements in Organometallic Chemistry, 17 (1979) 319. 
In addition, Kirk-Othmer describes transition metal catalyst suitable for 
hydrogenation in the Encyclopedia of Chemical Technology (1978) at volume 
6, p. 793 and volume 4, p. 842, which include nickel, cobalt, platinum, 
palladium, chromium, zinc, rhodium and molybdenum. Complexes of these 
transition metals are utilized to provide catalysis of the hydrogenation 
reaction within a homogeneous system. Many of these transition metal 
complexes are sensitive to moisture and air and lose their activity in the 
homogeneous system very quickly. It is desirable to obtain a transition 
metal complex which exhibits greater stability within the reaction medium 
and is less susceptible to oxidation in the presence of air and moisture. 
Cyclometallated transition metal complexes have been described by Dehand 
and Pfeffer in Coordination Chemistry Reviews, 18 (1976) 327-352 and 
Michael Bruce, in Angew. Chem. Int. Ed. Eng., 16 (1977) 73-86, which are 
incorporated herein by reference. These references discuss various species 
of cyclometallated complexes, their syntheses, their physical properties 
and some chemical reactions of the ring structures of the cyclometallated 
complexes. The use of the cyclometallated complexes as hydrogenation 
catalysts has heretofore never been suggested. The cyclometallated 
complexes have never been employed in a catalytic system. 
SUMMARY OF THE INVENTION 
This invention provides a method for hydrogenating unsaturated hydrocarbons 
which comprises reacting an unsaturated hydrocarbon with hydrogen in a 
solution of cyclometallated complex catalyst at a temperature above about 
20.degree. C., 
said unsaturated hydrocarbon comprising less than about 50 mole percent of 
the reaction mixture and being selected from the group consisting of 
aliphatic and cyclic olefins and alkynes of from 2 to 10 carbon atoms, 
aromatic hydrocarbons of from 8 to 18 carbon atoms having olefinic or 
alkyne functionality within hydrocarbon radicals of from 2 to 4 carbon 
atoms and siloxanes of from 1 to 10 --(Si--O)-- units having olefinic or 
alkyne functionality within hydrocarbon radicals of from 2 to 4 carbon 
atoms, subject to the proviso that said unsaturated hydrocarbons contain 
no acidic functional groups, and 
said cyclometallated complex catalysts having a 4-6 membered ring with a 
chemically combined unit of the formula 
##STR1## 
wherein M is a transition metal, L is a ligand selected from the group 
consisting of phosphorus, nitrogen, arsenic, oxygen and sulfur and C is a 
covalently bonded carbon atom of a hydrocarbon species having at least 6 
carbon atoms. 
OBJECTS OF THE INVENTION 
An object of the present invention is to provide a catalyst for the 
hydrogenation of olefins and alkynes with reduced sensitivity to moisture 
and air. 
Another object of the present invention is to provide a homogeneous 
transition metal catalyst for the hydrogenation of olefins and alkynes 
which exhibits a longer lifetime than the hydrogenation catalysts 
previously utilized. 
Another object of the present invention is to provide a hydroganation 
catalyst which can be regenerated by the addition of starting materials 
and the use of higher temperatures. 
A further object of the present invention is to provide a cyclometallated 
transition metal complex catalyst which provides high conversion rates for 
the hydrogenation of olefins and alkynes. 
STATEMENT OF THE INVENTION 
The essential feature of the process comprising this invention is the use 
of cyclometallated transition metal complexes as catalysts. The terms 
"cyclometallated transition metal complex" and "cyclometallated complex", 
as used herein, refer to transition metal complexes which contain a ring 
system having a chemically combined unit of the formula 
##STR2## 
wherein L is a ligand selected from the group consisting of phosphorus, 
nitrogen, arsenic, oxygen and sulfur atoms, M is a transition metal and C 
is a covalently bonded carbon atom. A bond lies between the transition 
metal "M" and the ligand "L". A covalent bond lies between the transition 
metal and the carbon atom. The ligand "L" and carbon atom "C" are linked 
to provide a 4-6 membered ring structure with the transition metal. The 
carbon atom and ligand "L" are typically a part of one coordination 
complex that appears on the transition metal. The carbon atom is part of a 
hydrocarbon species having at least 6 carbon atoms, which is preferably an 
aromatic hydrocarbon and the ligand "L" is then bonded either directly or 
indirectly to this hydrocarbon species as part of a coordination complex. 
The transition metals are preferably selected from the group consisting of 
ruthenium, palladium, platinum, nickel, cobalt, rhodium, and manganese. 
The transition metal which is most preferred typically depends on the type 
of olefin which is hydrogenated. For the hydrogenation of unsaturated 
aliphatic hydrocarbons, ruthenium, palladium and cobalt are the most 
preferred transition metals. 
Suitable cyclometallated transition metal complexes and cyclometallated 
ring structures are described in J. Dehand and M. Pfeffer in 
"Cyclometallated Compounds", Coordination Chemistry Reviews, 18 (1976) 
327-352. Where nitrogen is the ligand, L, typical transition metals are 
nickel, palladium and platinum. A five-membered ring is formed with the 
nitrogen ligand having the formula 
##STR3## 
where the nitrogen ligand is sterically hindered and is typically 
tertiary. The ring structure is typically of the formulas 
##STR4## 
where Z is nitrogen or carbon. 
Where the ligand is phosphorus, the cyclic structure may have 4-6 members. 
Formula VII illustrates an example of a 4 membered cyclometallated complex 
having a phosphorus ligand. 
##STR5## 
Five-membered rings are formed preferentially, with the phosphorus ligand 
being sterically hindered. The five-membered ring typically has the 
formula shown below with the transition metal "M" being rhodium, 
palladium, platinum, cobalt and ruthenium. 
##STR6## 
More particular examples of cyclometallated complexes having phosphorus 
ligands are shown in formulas VIII and IX. 
##STR7## 
Included within the cyclometallated complexes having phosphorus ligands 
are the phosphites. 
##STR8## 
These typically have a five-membered cyclic structure of the formula 
below. 
##STR9## 
Examples of 5 membered cyclometallated transition metal complexes having a 
phosphite ligand are described with greater particularity by Dehand and 
Pfeffer in Table 4 of that reference on page 342, which include: 
##STR10## 
Formula XII illustrates an example of a cyclometallated complex having a 
phosphorous ligand with a 6 membered ring structure: 
##STR11## 
Other suitable cyclometallated transition metal complexes with phosphite 
ligands are shown in formulas XIII-XVI where Ph=phenyl. 
##STR12## 
and the ruthenium complex of formula XVII, which is a new composition of 
matter. 
##STR13## 
Cyclometallated complexes having arsenic, oxygen and sulphur ligands 
provide 5 membered ring structures of the general structures below 
##STR14## 
where Y is oxygen, sulphur or carbon. A particular cyclometallated complex 
with an arsenic ligand is shown in FIG. XVIII. 
##STR15## 
Particular cyclometallated complexes having oxygen and sulphur ligands are 
shown in formulas XX and XXI. 
##STR16## 
These cyclometallated catalysts have been found to be true homogeneous 
catalysts in accordance with the tests described by R. H. Crabtree et al 
in J.Amer.Chem.Soc., 104 (1982) 107. These tests involve the reduction of 
nitrobenzene to anilene and distinguish the homogeneous catalysts from 
heterogeneous catalysts, such as colloidal metals. 
In that the cyclometallated complexes operate as a homogeneous catalyst, 
they are dissolved within a solution during hydrogenation of the olefins 
and alkynes. The solutions are limited to inert solvents which dissolve 
the olefin and/or alkyne so as to permit exposure to the catalyst during 
reaction. Nonreactive solvents are required to maintain catalyst activity. 
The cyclometallated compounds retain their activity in most nonpolar 
organic solvents. Examples of suitable inert, nonpolar solvents include 
unsubstituted aromatic hydrocarbons, such as benzene, toluene and xylene. 
Aromatic nonpolar solvents are preferred. Unsubstituted aliphatic 
hydrocarbons are sufficiently inert; however, the olefins are not very 
soluble in most of these solutions. Polar solvents may be sufficiently 
inert where the polar group is not a hydroxy radical. Certain halogenated 
hydrocarbons may be too reactive, such as chloroform; while others are 
sufficiently inert under mild reaction conditions, such as methylene 
chloride. Other polar solvents which may be sufficiently inert are 
selected ketones, such as acetone. Mixtures of inert organic solvents are 
also suitable. The organic solvents which are preferred depend on the 
olefins and/or alkynes to be hydrogenated. Those inert organic solvents 
having a boiling point distinct from the reaction product are most 
preferred with toluene being preferred most often. 
The catalysts retain their activity over a wide temperature range. The 
hydrogenation reaction preferably proceeds at a temperature within the 
range of about 20.degree. C. to 220.degree. C. Although higher and lower 
temperatures can be utilized, product yields are reduced due to either low 
reactivity at low temperatures or degradation of the hydrogenation product 
at high temperatures. The lower limit for the temperature is the minimum 
temperature at which the catalyst and olefin remain active. For a given 
catalyst, different temperatures may be necessary when hydrogenating 
different olefins or alkynes. The upper limit is the temperature at which 
the cyclometallated complex degrades. The most preferred reaction 
temperatures fall within the range of about 100.degree. to 200.degree. C. 
The quantity of catalyst which is preferred falls within the range of 0.01 
to 1.0 mole percent of the active ingredients, with a range of about 0.05 
to 0.3 mole percent being most preferred. The actual metal concentration 
within the reaction mixture is preferably in the order of about 0.005 to 
0.03% by weight active ingredients. 
An embodiment of this invention is directed to a new composition of matter 
having the formula XVII shown above. This catalyst was formed by reacting 
RuHCl(PPh.sub.3).sub.3 and excess tri-ortho-tolyl-phosphite. This reaction 
typically takes place in an organic solution, such as hexane, heptane and 
the like under a nitrogen blanket at a temperature in the range of about 
60.degree.-100.degree. C. The product yield is purified by extraction with 
heptane and recrystallization from toluene/hexane mixtures. 
The unsaturated hydrocarbon species which can be reacted include aliphatic 
and cyclic olefins and alkynes of from 2 to 10 carbon atoms. Hydrogenation 
of larger aliphatic and cyclic olefins and alkynes may be accomplished 
where the carbon unsaturation falls within the terminal portions of the 
hydrocarbon chain. Aromatic hydrocarbons of 8-18 carbon atoms having 
olefin or alkyne functionality can also be hydrogenated at the olefin or 
alkyne moieties. The ring structure of the aromatic hydrocarbon remains 
intact after hydrogenation, only the olefin or alkyne moieties are 
hydrogenated. Olefin and alkyne moieties on siloxanes of 1 to 10 
--(Si--O)-- units may be hydrogenated by the process comprising this 
invention. The siloxane polymer backbone remains intact after 
hydrogenation, with only the olefin or alkyne moieties being hydrogenated. 
The olefin and alkyne moieties on the aromatic hydrocarbons and the 
siloxanes are preferably radicals of from 2 to 4 carbon atoms. Where the 
radical has more than 4 carbon atoms, hydrogenation of olefin or alkyne 
functionality which is not on the terminal portions of the radical may be 
difficult due to steric effects. Hydrocarbons with acidic groups, such as 
carboxyl groups, will inactivate the cyclometallated complex so as to 
provide little or no hydrogenation. However, unsaturated hydrocarbons 
which contain non-acidic functional groups are suitable for use in this 
invention. For example, esters of the formula below are suitable 
##STR17## 
where R.sup.a is a hydrocarbon radical of from 1 to 8 carbon atoms. 
The unsaturated hydrocarbons preferably comprise less than about 50 mole 
percent of the reaction mixture so as to enhance the percentage converted 
to saturated hydrocarbons. At very high concentrations, the unsaturated 
hydrocarbon may flood the cyclometallated catalysts and a portion may 
escape the reaction medium without hydrogenating. Typical olefins which 
can be hydrogenated include ethylene, propylene, butylene, pentene, 
hexene, heptene, cyclo-hexene, styrene, divinyl-tetramethyldisiloxane, and 
the like. Typical alkynes which can be hydrogenated include ethyne, 
propyne, butyne, pentyne, hexyne, and the like. 
The quantity of hydrogen utilized in the reaction mixture is preferably at 
a value which will hydrogenate all of the olefins or alkynes within the 
reaction medium. However, any quantity of hydrogen will provide reaction 
in the presence of a cyclometallated catalyst. It is most preferable to 
utilize a slightly excessive quantity of hydrogen, such as about 2 to 2.5 
moles per mole of unsaturated hydrocarbon linkages. 
The order in which the reactants, hydrogen and the unsaturated hydrocarbon, 
are exposed to the cyclometallated catalyst is critical. Where hydrogen is 
the initial reactant introduced into the reaction medium containing the 
catalyst, hydrogenation of the subsequently introduced unsaturated 
hydrocarbon is very low and often eliminated. It is believed that the 
addition of hydrogen prior to the addition of the unsaturated hydrocarbon 
inactivates the catalyst by opening the ring structure. Without the 
cyclometallated ring structure, the catalytic activity of many transition 
metals is lost. For example, where the transition metal is cobalt, no 
reaction takes place except within cyclic complexes. In addition, 
palladium complexes do not provide catalysis unless in cyclic form. Where 
the transition metal exhibits catalytic activity in non-cyclometallated 
form, such as ruthenium, the cyclometallated form shows higher activity at 
room temperature and improved resistance to oxidative degradation. Where 
the order of addition is reversed, i.e. the olefin is introduced initially 
followed by hydrogen addition, the ring structure remains intact and 
complete hydrogenation of the olefin is expected under preferred 
conditions. 
Although the cyclometallated catalysts show excellent resistance to 
degradation from exposure to moisture and air, it is preferable to perform 
the reaction over an inert atmosphere such as nitrogen or argon. The 
reaction solution need not be dried prior to use, but such a practice may 
be desirable for certain embodiments of this invention. 
Conventional pressurized reactors are suitable for use in this invention. 
The hydrogenation reaction is typically performed in a batchwise fashion. 
The cyclometallated catalysts will provide activity following 
hydrogenation of the initial batch of unsaturated hydrocarbon. The 
addition of more unsaturated hydrocarbon and hydrogen to a reaction medium 
at a suitable temperature will provide further hydrogenation. The 
cyclometallated catalyst can be expected to provide over 300 batch cycles 
or turnovers without a significant loss in activity.

The following examples are provided to illustrate embodiments of this 
invention and are not intended to limit the scope of this invention to 
their contents. 
EXAMPLE 1 
Toluene (15 ml) and a ruthenium catalyst of Formula XIII (0.116 grams, 
0.084 mmol) were combined in a 250 milliliter thickwalled glass bottle. 
The bottle was degassed with nitrogen and then pressurized with ethylene 
(50 psi, 33 mmol) and then hydrogen (50 psi, 33 mmol). The bottle was 
heated with stirring to 180.degree. C. for 4 hours. After cooling to room 
temperature, the gas above the solution was analyzed by infrared 
spectroscopy, which showed ethane was produced quantitatively, i.e. 
greater than 90% ethane present. 
The solution from this reaction remained in the 250 ml thickwalled glass 
bottle and was recharged with ethylene (50 psi, 33 mmol) and hydrogen (60 
psi, 39 mmol). The bottle was heated with stirring to 205.degree. C. for 5 
hours. The bottle was cooled to room temperature and a pressure of about 
60 psi. Analysis of the gases by infrared spectrometry showed greater than 
90% ethane present in the recovered gas. The reaction solution was then 
recovered from the bottle and filtered through 0.5 micron filter; the 
solution was found to be golden yellow at this point. The solution was 
then placed in a 90 ml bottle and charged with ethylene (50 psi, 10 mmol) 
and hydrogen (50 psi, 10 mmol). The bottle was heated with stirring for 6 
hours at 170.degree. C. The gases recovered from solution were analyzed by 
infrared spectrometry and showed to contain greater than 90% ethane. 
EXAMPLE 2 
This example illustrates the synthesis and utility of the cyclometallated 
complex of formula XVII. Hexane (30 ml), the complex 
RuHCl(PPh.sub.3).sub.3 (1.05 g, 1.08 mmol), where Ph=phenyl, and excess 
tri-ortho-tolyl phosphite (3.5 ml, 11 mmol) were combined in a 250 ml 
round bottom flask. The solution was degassed with N.sub.2 and refluxed 
for 30 minutes. The solution was filtered to recover an orange solid. The 
solid was purified by extraction with heptane and recrystallized from 
toluene/hexane. The ruthenium complex of formula XVII was obtained in 50% 
yield as an orange solid, having a melting point of 165.degree. C. 
(decomp). Elemental analysis indicated C=67.24, H=4.94, P=8.95 and 
Ru=9.91. Calculated values were C=67.62, H=4.94, P=9.19 and Ru=9.99. 
Proton NMR in CDCl.sub.3 gave peaks at 7.75, 6.67, 6.14, 1.88 and 1.68 
PPM. Phosphorus NMR in CDCl.sub.3 gave peaks at 167.71 (t,J=45 Hz) and 
41.80 (d,J=45 Hz). 
Toluene (10 ml) and a cyclometallated catalyst of formula XVII (0.088 g, 
0.087 mmol) were placed in a 90 ml thickwalled glass bottle. The bottle 
was degassed with nitrogen and charged with ethylene (50 psi, 11 mmol) and 
then hydrogen (50 psi, 11 mmol). The contents of the bottle were stirred 
for 8 hours at 25.degree. C. The gas above the solution was analyzed by 
infrared spectroscopy which showed ethane was produced quantitatively. The 
cyclometallated catalyst of formula XVII was recovered from the solution 
with no evidence of change. 
CONTROL 
Toluene (50 ml) was placed in a 90 ml thickwalled glass bottle. The bottle 
was degassed with nitrogen and then charged with ethylene (50 psi, 11.8 
mmol) and then hydrogen (50 psi, 12 mmol). The bottle was heated with 
stirring to 190.degree. C. for 41/2 hours. The bottle was cooled to room 
temperature and a pressure of 80 psi. The gases were analyzed by infrared 
spectroscopy and found to contain only ethylene. No evidence of 
hydrogenation having occurred within the bottle was present. 
HYDROGEN AS INITIAL REACTANT 
Toluene (5 ml) and a cyclometallated catalyst of formula XIII (0.0187 gms, 
0.0136 mmol) were added to a 90 ml thickwalled glass bottle. The bottle 
was degassed with nitrogen and then charged first with hydrogen (50 psi, 
11.8 mmol) and then ethylene (50 psi, 11.8 mmol). The bottle was heated to 
180.degree. C. with stirring for 2 hours. The reaction was cooled and the 
gases were analyzed by infrared spectroscopy. Infrared analysis indicated 
that hydrogenation within the glass bottle of the ethylene was slight in 
that the gases comprised mostly ethylene. 
COMATIVE EXAMPLE 
This example illustrates hydrogenation of olefins utilizing a catalyst with 
no cyclometallated ring structure. The catalyst utilized was 
RuHCl(PPh.sub.3).sub.3, with Ph=phenyl. 
To 10 ml of toluene were added 0.102 grams (0.11 mmol) of the 
non-cyclometallated catalyst described above. The solution was maintained 
in a 90 ml thickwalled glass bottle, which was degassed with nitrogen and 
then charged with ethylene (45 psi, 8.9 mmol) and hydrogen (45 psi, 8.9 
mmol). The bottle was stirred at room temperature for 2 hours until a 
pressure of 45 psi was obtained. Analysis of the gases by infrared 
spectrometry showed a 50--50 mixture of ethylene:ethane. Proton NMR 
suggested degradation of the catalyst occurred. Repressurizing with 
H.sub.2 and ethylene resulted in no further hydrogenation. 
This is a significant contrast from the results obtained from the 
cyclometallated species of formula XVII, which did not degrade and 
provided a higher degree of conversion. 
EXAMPLE 3 
Toluene (5 ml) and a cyclometallated complex of formula XVII (0.011 gms, 
0.011 mmol) were combined in a 90 ml thick walled glass bottle. Styrene (1 
ml, 8.75 mmol) was added to the solution and the bottle was sealed. The 
bottle was then pressurized with hydrogen (80 psi) and heated to 
165.degree. with stirring for 31/2 hours. After cooling, the solution was 
analyzed by gas chromatography, which showed a 96% conversion to ethyl 
benzene. 
EXAMPLE 4 
Toluene (5 ml) and a cyclometallated complex of formula XVII (0.13 gms, 
0.13 mmol) were combined in a 90 ml thick walled glass bottle. Vinyl 
acetate (1 ml, 0.011 mol) was added to this solution and the bottle was 
sealed, pressurized with hydrogen (80 psi, 19 mmol) and heated to 
170.degree. C. for 2 hours with stirring. After cooling, gas chromatograph 
analysis showed 20% conversion to ethyl acetate. 
COMATIVE EXAMPLE 
Toluene (5 ml) and a noncyclometallated catalyst of the formula 
ClRh(PPh.sub.3).sub.3, where Ph=phenyl, (0.0174 grams, 0.019 mmol) were 
combined in a 90 ml thick walled glass bottle. The vinyl acetate (1 ml, 
0.011 mol) was added to the solution and the bottle was sealed, 
pressurized with hydrogen (80 psi, 19 mmol) and heated to 160.degree. C. 
for 2 hours with stirring. After cooling, gas chromatograph analysis 
showed 13% conversion to ethyl acetate. 
EXAMPLE 5 
Toluene (5 ml) and a cyclometallated complex of formula XVII (0.0369, 0.030 
mmol) were combined in a 90 ml thick walled glass bottle. Cyclohexene (1 
ml, 9.9 ml) was added to the solution and the bottle was sealed, 
pressurized with hydrogen (50 psi, 11.7 mmol) and heated to 130.degree. 
for 5 hours with stirring. After cooling, gas chromatograph analysis 
showed that 100% conversion to cyclohexane had occurred. 
The ability of the complex to catalyze the hydrogenation of nitrobenzene to 
analine has been shown by Crabtree et al, in the reference cited above, to 
be an operational test for the presence of metal colloids. Failure to 
catalyze this reaction is good evidence that the catalyst is truly 
homogeneous. 
Nitrobenzene (1 ml) was added to the catalyst solution described above. The 
solution was pressurized with hydrogen (50 psi) and heated to 120.degree. 
C. for 4 hours with stirring. After cooling, gas chromatograph analysis 
showed only a trace (less than 3%) of aniline, which is consistent with 
the cyclometallated catalyst of formula XVII being truly homogeneous. 
COMATIVE EXAMPLE 
The complex ClRh(PPh.sub.3).sub.3, wherein Ph is phenyl, (0.033 gms, 0.036 
mmol) was combined with toluene (5 ml) and cyclohexene (1 ml, 9.9 mmol). 
The complex described above was a noncyclometallated species. The bottle 
was sealed, pressurized with hydrogen (50 psi, 11.7 mmol) and heated to 
130.degree. C. for 5 hours with stirring. Gas chromatograph analysis 
showed 80% conversion to cyclohexane had occurred. 
This catalyst was analyzed to determine whether it is truly homogeneous. 
Nitrobenzene (1 ml) was added to the above solution within a 90 ml thick 
walled glass bottle. The bottle was pressurized with hydrogen (50 psi) and 
heated to 110.degree. C. for 45 minutes with stirring. After cooling, gas 
chromatograph analysis showed 29% conversion to aniline. These results are 
consistent with a portion of the catalysts being an active rhodium colloid 
within the solution. Therefore, the complex ClRh(PPh.sub.3).sub.3, where 
Ph is phenyl, is not a truly homogeneous catalyst under these conditions. 
EXAMPLE 6 
Toluene (5 ml) and a cyclometallated complex of formula XVII (0.0339, 0.032 
ml) were combined in a 90 ml thick walled glass bottle. To this solution 
were added 4.4 ml (1 ml) of 1,3-divinyl-tetramethyldisiloxane. The bottle 
was then sealed, pressurized with hydrogen (45 psi, 10.6 mmol) and heated 
to 120.degree. C. for 3 hours with stirring. After cooling, gas 
chromatograph analysis showed the following materials present: 
1,3-divinyl-tetramethyl-disiloxane (10.3%), 1-ethyl, 
3-vinyl-tetramethyldisiloxane (20.8%) and 
1,3-diethyl-tetramethyl-disiloxane (68.9%). The identity of the latter two 
products was confirmed by GCMS analysis. 
EXAMPLE 7 
Toluene (5 ml) and a cyclometallated complex catalyst of formula XVII 
(0.010 gms, 1.0199 mmol) were combined in a 90 ml thick walled glass 
bottle. To this bottle were added 5.1 mmol (0.5 ml) of 1 pentyne. The 
bottle was sealed, pressurized with hydrogen (50 psi, 11.7 ml) and stirred 
at room temperature for 48 hours. Gas chromatograph analysis at this point 
showed 10% conversion to a 1:1 mixture of 1-pentene and n-pentane had 
occurred. The contents of the bottle were repressurized with hydrogen (50 
psi) and heated to 110.degree. C. for 17 hours with stirring. After 
cooling, gas chromatograph analysis showed a complete conversion to a 
mixture of about 1:1 n-pentane and pentenes (a mixture of 1-pentene (67%) 
and 2-pentene (33%)). This solution was once again repressurized with 
hydrogen (50 psi) and heated to 155.degree. C. for 4 hours with stirring. 
Gas chromatograph analysis showed that 1 pentene was selectively 
hydrogenated to n-pentane. 
EXAMPLE 8 
To a 250 ml thickwalled glass bottle were added 1-hexene (4 ml, 32.9 mmol) 
and a catalyst of formula XIII (0.051 gms, 0.37 mmol). The bottle was 
degassed with nitrogen, charged with hydrogen (100 psi, 69.5 mmol), heated 
to 156.degree. C. and stirred for 15 hours. The bottle was then cooled to 
room temperature and a pressure of 55 psi. The contents were recovered and 
analyzed by gas chromatograph analysis and GCMS which showed that n-hexane 
was produced in 100% yield. 
EXAMPLE 9 
Toluene (15 ml) and a noncyclometallated catalyst of the formula 
CoH[P(OPh).sub.3 ].sub.4 (0.09 gms, 0.075 mmol), with Ph=phenyl, were 
placed in a 90 ml thickwalled glass bottle. The bottle was degassed with 
nitrogen and then charged with ethylene (50 psi, 10 mmol) and hydrogen (50 
psi, 10 mmol). The bottle was heated with stirring to 210.degree. C. for 5 
hours. The solution was colorless and a dark precipitate formed within the 
solution. The gases were analyzed by infrared spectrometry and found to 
contain 100% ethylene. 
To 10 ml of toluene were added a cobalt cyclometallated catalyst of formula 
XV (0.087 gms, 0.067 mmol). The solution was placed in a 90 ml glass 
bottle and degassed with nitrogen. The bottle was then charged with 
ethylene (50 psi, 11 mmol) and hydrogen (50 psi, 11 mmol). The bottle was 
heated with stirring at 207.degree. C. for 4 hours. Analysis of the gases 
by infrared spectrometry showed greater than 90% ethane. 
The hydrogenation of 1-hexene was carried out in the presence of 0.116 gms 
(8.9 mmol) of the cyclometallated catalyst of formula XV. A solution of 10 
ml of benzene was placed in a 90 ml thickwalled glass bottle which was 
charged with hydrogen (80 psi, 18 mmol) and heated with stirring to 
85.degree. C. for three hours. The quantity of hexene was utilized was 1 
milliliter (7.9 mmol). After reaction, the bottle was cooled to room 
temperature and vented. The solution was analyzed by gas chromatography 
which showed n-hexane with no hexene present. The solution was filtered 
and returned to the 90 ml glass bottle and recharged with a similar 
quantity of hexene and hydrogen. The bottle was stirred with heating for 
41/2 hours at 190.degree. C. The solution was found to contain n-hexane 
with no hexene present. 
EXAMPLE 10 
To 10 ml of toluene were added 0.06 gms of a noncyclometallated catalyst 
having the formula PdCl.sub.2 [P(OPh).sub.3 ].sub.2 (0.083 mmol). The 
solution was placed within a 90 ml thickwalled glass bottle which was 
degassed with nitrogen and charged with ethylene (50 psi, 11 mmol) and 
hydrogen (50 psi, 11 mmol). The bottle was heated with stirring to 
192.degree. C. for 6 hours. A palladium mirror formed in the bottle and 
analysis of the gases showed that only ethylene was present. 
A palladium cyclometallated catalyst having the formula XVI (0.069 gms, 
0.091 mmol) was added with 10 ml toluene in a glove box and placed in a 90 
ml glass bottle. The bottle was charged with ethylene (50 psi, 11 mmol) 
and hydrogen (50 psi, 11 mmol) and then heated to 192.degree. C. for four 
hours. After the reaction, a dark precipitate was present. The gases were 
analyzed by infrared spectrometry and shown to contain greater than 90% 
ethane. The solution was taken into the glove box and filtered through a 
0.5 micron filter. The filtrate was returned to a 90 ml glass bottle which 
was recharged with 1-hexene (0.9 ml, 7 mmol) and hydrogen (100 psi, 24 
mmol). The bottle was heated with stirring at 180.degree. C. for eight 
hours. The solution was analyzed by gas chromatography and found to 
contain n-hexane with no hexene present. 
Although the above examples have shown various modifications of the present 
invention, further modifications are possible by one skilled in the art 
without departing from the scope and spirit of this invention.