Hydrosilation of the manganese acetyl (CO){sub 5}MnC(O)CH{sub 3} with monohydrosilanes
- Rensselaer Polytechnic Inst., Troy, NY (United States)
Treatment of the manganese acetyl (CO){sub 5}MnC(O)CH{sub 3} (1) with 1-2 equiv of a monohydrosilane furnished mixtures of {alpha}-siloxyethyl (CO){sub 5}MnCH(OSiR{sub 3})CH{sub 3} (2) and {alpha}-siloxyvinyl (CO){sub 5}MnC(OSiR{sub 3})=CH{sub 2} (3) complexes. Relative yields of 2 and 3 varied from 80% and 6% for HSiMe{sub 2}Ph to 28% and 59% for HSiEt{sub 3}. Mechanistic studies on the HSiMe{sub 2}Ph and HSiEt{sub 3} hydrosilation of 1 are noteworthy for (1) the absence of (R{sub 3}SiO)CH=CH{sub 2} and CH{sub 3}CH{sub 2}OSiR{sub 3} byproducts, (2) the presence of 3 but not (CO){sub 5}MnSiR{sub 3}, (3) inhibition by CO, phosphine, or acetonitrile, but neither air nor light, (4) competitive hydrosilation of other substrates (e.g., acetone or Cp(CO){sub 2}FeC(O)R) for which 1 is a precatalyst, (5) degradation of 2 by excess HSiR{sub 3}, giving Mn{sub 2}(CO){sub 10} and (R{sub 3}Si){sub 2}O as the final products, (6) the fact that this degradation results in autocatalysis by generating the transient active catalyst (CO){sub 4}MnSiR{sub 3} (15), and (7) the fact that the hydrosilation induction period can be removed by independently generating the putative 15. These observations are consistent with an autocatalytic hydrosilation mechanism in which silane degradation of product 2 (or of other manganese complexes) generates the active catalyst 15, which binds 1 and rearranges to the unsaturated bimetallic {mu}-siloxyethylidene (CO){sub 5}MnC(CH{sub 3})(OSiMe{sub 2}Ph)Mn(CO){sub 4} as the key catalysis intermediate: silane addition affords 2 whereas {beta}-deinsertion produces 3. 54 refs., 4 figs., 2 tabs.
- OSTI ID:
- 420830
- Journal Information:
- Journal of the American Chemical Society, Journal Name: Journal of the American Chemical Society Journal Issue: 42 Vol. 118; ISSN JACSAT; ISSN 0002-7863
- Country of Publication:
- United States
- Language:
- English
Similar Records
Manganese carbonyl complexes as catalysts for the hydrosilation of ketones: Comparison with RhCl(PPh{sub 3}){sub 3}
Catalytic hydrosilation of organic esters using manganesecarbonyl acetyl complexes, (L)(CO){sub 4}MnC(O)CH{sub 3} (L=CO,PPh{sub 3})