THE REACTIONS OF HYDROSILANES WITH THE METHOXYCARBONYL COMPLEXES CP(L)(CO)MCO2ME (M = FE, RU L = CO, PPH3) AND (L)(CO)(X)MCO2ME (M = CO, MNL = CO, PPH3 X = 3,4, WITH AND WITHOUT CATALYSIS

The reactivity of selected organotransition metal methoxycarbonyl comp lexes towards hydrosilanes differs significantly from their acetyl ana logs in that hydrosilation does not occur across the methoxycarbonyl l igand. Only hydrosilane/manganese carbonyl precatalyst systems that ha d proved to be more active towards the acetyl ligand on Cp(L)(CO)MC(O) CH3 (M = Fe, Ru; L = CO,PPh3, PPh3) reacted with the methoxycarbonyl c omplexes Cp(CO)(2)MCO2CH3 (1, M = Fe; 2, M = Ru). These reactions invo lving PhSiH3/2-3%(PPh3)(CO)(4)MnC(O)CH3 for 1 and 2, or PhMe2SiH/2-3% (CO)(5)MnCH3 for 1 afforded their eta(4)-cyclopentadiene compounds (et a(4)-C5H6)M(CO)(3) (M = Fe,Ru) plus methoxysilanes. Results with PhMe2 SiD/3% (CO)(5)MnCH3 support exo deuteride transfer to the Cp ligand; a mechanism is proposed. The low reactivity of methoxycarbonyl complexe s under hydrosilation catalysis conditions also is consistent with the inactivity of PhSiH3 or Ph2SiH2/Rh(PPh3)(3)Cl towards 1 or 2 and with the inertness of Cp(PPh3)(CO)FeCO2CH3 and Cp(CO)(2)FeCO2CH3 under al l attempted hydrosilation conditions. This diminution of hydrosilane r eactivity extends to cobalt and manganese carbonyl methoxycarbonyl com plexes (L)(CO)(x)MCO2CH3 (3, M=Mn, x=4, L=CO; 4, M=Co, x=3, L=PPh3; 5, M=Co, x=3, L=CO). Although their acetyl analogs (L)(CO)(x)MC(O)CH3 ar e sensitive to hydrosilanes, both 3 and 4 are inert towards PhMe2SiH o r Ph2SiH2. Treatment of 5 with PhMe2SiH released methyl formate and le ft the silyl complex (CO)(4)CoSiMe2Ph, a result that resembles the hyd rogenation chemistry of 5. (C) 1997 Elsevier Science S.A.