INSERTION REACTIONS OF ELECTROPHILIC IRON CARBENE COMPLEXES WITH ORGANOSILANES - A SYNTHETIC AND MECHANISTIC STUDY

Cationic iron carbene complexes of the type Cp(L)(CO)Fe=C(H)(R)(+)(L=PPh(3), R=CH3,Ph), (L=PEt(3), R=Ph, CH3, CH2CH3, CH2CH2CH2CH3, CH2CH2CH2CH2CH2CH3) have been prepared and shown to react with organosilanes to give the products resulting from insertion of the carbene unit into the Si-H bond. These reactions occur rapidly at low temperature, but yields are ca. 50% and a counterion-dependent by-product is formed. A mechanism consistent with the experimental observations is proposed. Variable temperature NMR studies are reported which have allowed for the independent observation of several of the intermediates proposed in the mechanistic pathway.