Catalytic hydrogenation using complexes of base metals with tridentate ligands
Complexes of cobalt and nickel with tridentate ligand PNHP R are effective for hydrogenation of unsaturated compounds. Cobalt complex [(PNHP Cy )Co(CH 2 SiMe 3 )]BAr F 4 (PNHP Cy =bis[2-(dicyclohexylphosphino)ethyl]amine, BAr F 4 =B(3,5-(CF 3 ) 2 C 6 H 3 ) 4 )) was prepared and used with hydrogen for hydrogenation of alkenes, aldehydes, ketones, and imines under mild conditions (25-60° C., 1-4 atm H 2 ). Nickel complex [(PNHP Cy )Ni(H)]BPh 4 was used for hydrogenation of styrene and 1-octene under mild conditions. (PNP Cy )Ni(H) was used for hydrogenating alkenes.
1. A process for hydrogenation of an unsaturated compound, the process comprising:
combining a composition comprising a compound of Formula 1 with hydrogen and an unsaturated compound under conditions effective for the hydrogenation of the unsaturated compound:
wherein:
each R 1 is independently selected from cycloalkyl, alkyl, substituted alkyl, phenyl, or substituted phenyl;
R 2 is —CH 2 Si(CH 3 ) 3 , H, alkyl, substituted alkyl, phenyl, substituted phenyl, alkoxide, or amido; and
M is cobalt or nickel.
2. The process of claim 1 , wherein R 2 is —CH 2 Si(CH 3 ) 3 , H, or alkyl.
3. The process of claim 1 , wherein R 2 is —CH 2 Si(CH 3 ) 3 , H, CH 3 , or CH 2 (CH 2 ) 6 CH 3 .
4. The process of claim 1 , wherein the unsaturated compound comprises:
a carbon-carbon double or triple bond that becomes hydrogenated as a result of the process,
a carbon-oxygen double bond that becomes hydrogenated as a result of the process, or
a carbon-nitrogen double or triple bond that becomes hydrogenated as a result of the process.
5. The process of claim 1 , wherein the combining the composition with hydrogen further comprises adding Hg or water.
6. The process of claim 1 , wherein the combining the composition of Formula 1 with hydrogen comprises combining a solution of the composition with the hydrogen and the unsaturated compound.
7. A process for hydrogenation of an unsaturated compound, the process comprising:
combining a composition comprising a compound of Formula 1 or Formula 2 with hydrogen and an unsaturated compound under conditions effective for the hydrogenation of the unsaturated compound:
wherein:
each R 1 is independently selected from cyclohexyl, isopropyl, adamantyl, or phenyl;
R 2 is —CH 2 Si(CH 3 ) 3 , H, alkyl, substituted alkyl, phenyl, substituted phenyl, alkoxide, or amido;
M is cobalt or nickel; and
X is a counterion.
8. The process of claim 7 , wherein R 2 is —CH 2 Si(CH 3 ) 3 , H, or alkyl.
9. The process of claim 7 , wherein R 2 is —CH 2 Si(CH 3 ) 3 , H, CH 3 , or CH 2 (CH 2 ) 6 CH 3 .
10. The process of claim 7 , wherein the unsaturated compound comprises:
a carbon-carbon double or triple bond that becomes hydrogenated as a result of the process,
a carbon-oxygen double bond that becomes hydrogenated as a result of the process, or
a carbon-nitrogen double or triple bond that becomes hydrogenated as a result of the process.
11. The process of claim 7 , wherein the combining the composition of Formula 1 or Formula 2 with hydrogen further comprises adding Hg or water.
12. The process of claim 7 , wherein the combining the composition of Formula 1 or Formula 2 with hydrogen comprises combining a solution of the composition of Formula 1 or Formula 2 with the hydrogen and the unsaturated compound.
13. The process of claim 7 , wherein the compound comprises: (PNP Cy )Co(CH 2 SiMe 3 ),
[(PNHP Cy )Co(CH 2 SiMe 3 )][X],
(PNP Cy )Co(H),
[(PNHP Cy )Co(H)][X],
(PNP Ad )Co(CH 2 SiMe 3 ),
[(PNHP Ad )Co(CH 2 SiMe 3 )][X],
(PNP iPr )Co(CH 2 SiMe 3 ),
[(PNHP iPr )Co(CH 2 SiMe 3 )][X],
(PNP Cy )Ni(H),
[(PNHP Cy )Ni(H)][X],
(PNP Cy )Ni(CH 2 (CH 2 ) 6 CH 3 ),
[(PNHP Cy )Ni(CH 2 (CH 2 ) 6 CH 3 )][X],
(PNP Cy )Ni(CH 3 ), or
[(PNHP Cy )Ni(CH 3 )][X],
wherein:
Cy is cyclohexyl,
Ad is adamantyl,
iPr is isopropyl, and
X is tetraphenylborate, hexafluorophosphate, B(C 6 F 5 ) 4 , or B(3,5-(CF 3 ) 2 C 6 H 3 ) 4 .
14. The process of claim 13 , wherein X is tetraphenylborate or hexafluorophosphate.
15. A composition comprising a compound represented by Formula 1 or Formula 2:
wherein:
each R 1 is independently selected from cyclohexyl, isopropyl, adamantyl, or phenyl;
R 2 is —CH 2 Si(CH 3 ) 3 , H, alkyl, substituted alkyl, phenyl, substituted phenyl, alkoxide, or amido;
M is cobalt or nickel; and
X is a counterion.
16. The composition of claim 15 , wherein R 2 is —CH 2 Si(CH 3 ) 3 , H, or alkyl.
17. The composition of claim 15 , wherein R 2 is —CH 2 Si(CH 3 ) 3 , H, CH 3 , or CH 2 (CH 2 ) 6 CH 3 .
18. The composition of claim 15 , wherein the compound is represented by Formula 2 in which the counterion X is tetraphenylborate, hexafluorophosphate, B(C 6 F 5 ) 4 , or B(3,5-(CF 3 ) 2 C 6 H 3 ) 4 .
19. The composition of claim 15 , wherein the compound comprises:
(PNP Cy )Co(CH 2 SiMe 3 ),
[(PNHP Cy )Co(CH 2 SiMe 3 )][X],
(PNP Cy )Co(H),
[(PNHP Cy Y)Co(H)][X],
(PNP Ad )Co(CH 2 SiMe 3 ),
[(PNHP Ad )Co(CH 2 SiMe 3 )][X],
(PNP iPr )Co(CH 2 SiMe 3 ),
[(PNHP iPr )Co(CH 2 SiMe 3 )][X],
(PNP Cy )Ni(H),
[(PNHP Cy )Ni(H)][X],
(PNP Cy )Ni(CH 2 (CH 2 ) 6 CH 3 ),
[(PNHP Cy )Ni(CH 2 (CH 2 ) 6 CH 3 )][X],
(PNP Cy )Ni(CH 3 ), or
[(PNHP Cy )Ni(CH 3 )][X],
wherein:
Cy is cyclohexyl,
Ad is adamantyl,
iPr is isopropyl, and
X is tetraphenylborate, hexafluorophosphate, B(C 6 F 5 ) 4 , or B(3,5-(CF 3 ) 2 C 6 H 3 ) 4 .
20. The composition of claim 19 , wherein X is tetraphenylborate or hexafluorophosphate.