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=P Ph(3), R=CH3,Ph), (L=PEt(3), R=Ph, CH3, CH2CH3, CH2CH2CH2CH3, CH2CH2CH 2CH2CH2CH3) have been prepared and shown to react with organosilanes t o give the products resulting from insertion of the carbene unit into the Si-H bond. These reactions occur rapidly at low temperature, but y ields are ca. 50% and a counterion-dependent by-product is formed. A m echanism consistent with the experimental observations is proposed. Va riable temperature NMR studies are reported which have allowed for the independent observation of several of the intermediates proposed in t he mechanistic pathway.