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Synthesis of a Silyl Cobalt Hydride and Its Catalytic Performance in Kumada Coupling Reactions.
- Source :
- Chemistry - An Asian Journal; 6/1/2017, Vol. 12 Issue 11, p1234-1239, 6p
- Publication Year :
- 2017
-
Abstract
- Four silyl [P,Si]-chelate cobalt complexes ( 2- 5) have been synthesized through the chelate-assisted Si−H activation of bidentate preligand ortho-HSi(Me)<subscript>2</subscript>(PPh<subscript>2</subscript>)C<subscript>6</subscript>H<subscript>4</subscript> ( 1) with CoMe(PMe<subscript>3</subscript>)<subscript>4</subscript> and CoCl(PMe<subscript>3</subscript>)<subscript>3</subscript>. The silyl Co<superscript>I</superscript> complex, Co(PMe<subscript>3</subscript>)<subscript>3</subscript>(1-Si(Me)<subscript>2</subscript>-2-(PPh<subscript>2</subscript>)C<subscript>6</subscript>H<subscript>4</subscript>) ( 2), was synthesized by Si−H activation of 1 with CoMe(PMe<subscript>3</subscript>)<subscript>4</subscript> or by combining complex 5 with MeLi and PMe<subscript>3</subscript>. Complex 2 was treated with CH<subscript>3</subscript>I or EtBr, generating the silyl Co<superscript>II</superscript> products CoI(PMe<subscript>3</subscript>)<subscript>2</subscript>(1-Si(Me)<subscript>2</subscript>-2-(PPh<subscript>2</subscript>)C<subscript>6</subscript>H<subscript>4</subscript>) ( 3) and CoBr(PMe<subscript>3</subscript>)<subscript>2</subscript>(1-Si(Me)<subscript>2</subscript>-2-(PPh<subscript>2</subscript>)C<subscript>6</subscript>H<subscript>4</subscript>) ( 4). The silyl Co<superscript>III</superscript> hydride, CoHCl(PMe<subscript>3</subscript>)<subscript>2</subscript>(1-Si(Me)<subscript>2</subscript>-2-(PPh<subscript>2</subscript>)C<subscript>6</subscript>H<subscript>4</subscript>) ( 5), was obtained by the reaction of complex 1 with CoCl(PMe<subscript>3</subscript>)<subscript>3</subscript>. The catalytic performance of complex 5 was explored for Kumada coupling reactions, showing good to excellent catalytic efficiency with 2 mol % catalyst loading for the reactions of aryl chlorides or aryl bromides with Grignard reagents. It is noteworthy that the synthesis of 5 as a chelate complex is easier than that of previously reported [PSiP]-pincer cobalt hydride. With similar catalytic efficiency for Kumada reactions, the catalyst loading (2 %) of 5 was lower than that (5 %) of [PSiP]-pincer cobalt hydride. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 18614728
- Volume :
- 12
- Issue :
- 11
- Database :
- Complementary Index
- Journal :
- Chemistry - An Asian Journal
- Publication Type :
- Academic Journal
- Accession number :
- 123439053
- Full Text :
- https://doi.org/10.1002/asia.201700144