Manganese carbonyl complexes as catalysts for the hydrosilation of ketones: Comparison with RhCl(PPh(3))(3)

Manganese carbonyl complexes catalyze the hydrosilation of ketones with PhMe(2)SiH and Ph(2)SiH(2) in C6D6 solutions. Efficacy of the manganese carbonyl precatalysts (2.4 mol %) toward acetone hydrosilation with 1.1 equiv of PhMe(2)SiH to give (CH3)(2)CH(OSiMe(2)Ph) (3) varied: (PPh(3))(CO)(4)MnC(O)...

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Bibliographic Details
Published inOrganometallics Vol. 15; no. 12; pp. 2764 - 2769
Main Authors Cavanaugh, MD, Gregg, BT, Cutler, AR
Format Journal Article
LanguageEnglish
Published WASHINGTON Amer Chemical Soc 11.06.1996
Subjects
Chemistry
Chemistry, Inorganic & Nuclear
Chemistry, Organic
Physical Sciences
Science & Technology
ORGANOIRON ACYL COMPLEXES
ASYMMETRIC HYDROSILYLATION
CHIRAL PHOSPHINE LIGANDS
ENANTIOSELECTIVE HYDROSILYLATION
TRANSITION-METAL COMPLEXES
MOLECULAR-STRUCTURE
COBALT CARBONYL
WILKINSON CATALYST
RHODIUM COMPLEXES
CIS LABILIZATION
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Summary:Manganese carbonyl complexes catalyze the hydrosilation of ketones with PhMe(2)SiH and Ph(2)SiH(2) in C6D6 solutions. Efficacy of the manganese carbonyl precatalysts (2.4 mol %) toward acetone hydrosilation with 1.1 equiv of PhMe(2)SiH to give (CH3)(2)CH(OSiMe(2)Ph) (3) varied: (PPh(3))(CO)(4)MnC(O))CH3 (1)(<5 min) >> (CO)(5)MnC(O)Ph > (CO)(5)MnC(O)CH3 > (CO)(5)MnCH3 > (CO)(5)MnBr (6.0 h) >> Mn-2(CO)(10) approximate to (PPh(3))(CO)(4)MnBr approximate to (CO)(5)MnSiMe(2)Ph (2). A turnover frequency of 27 min(-1) was measured for catalysis using 1% 1; rapid catalysis was possible with 0.1% 1 in the absence of solvent. As a precatalyst, 1 is much more reactive than Rh(PPh(3))(3)Cl for the PhMe(2)SiH hydrosilation of acetone, acetophenone, and cyclohexanone; both catalysts exhibit similar reactivity with Ph(2)SiH(2). With 1 as the precatalyst, isolated yields of the alkoxydimethylphenylsilanes exceeded 90%, with no evidence of competing dehydrogenative silation to yield vinyl silyl ethers. Photochemical activation of (CO)(5)MnSiMe(2)Ph (2) affords moderate hydrosilation catalytic activity in transforming acetone to a. In contrast, (CO)(4)CoSiMe(2)Ph (10) or Co-2(CO)(8) in the presence of the excess HSiMe(2)Ph, with or without photochemical activation, were ineffective acetone hydrosilation catalysts. A reaction pathway is presented for the manganese carbonyl-catalyzed hydrosilation of ketones that involves coordinatively unsaturated manganese silyl intermediates, (L)(CO)MnSiR''(3), as the active catalysts.
ISSN:0276-7333