Transition metal silyl complexes

The first examples were prepared by treatment of sodium cyclopentadienyliron dicarbonyl with trimethylsilyl chloride:[2] A related reaction is the oxidative addition of silyl halides.

The oxidative addition is preceded by the association of the intact hydrosilane with the unsaturated metal center, affording a sigma-silane complex, as discussed below.

Sigma bond metathesis can occur when hydrosilanes are treated with early metals alkyls.

Using the Petasis reagent, a cyclic dititanium complex is produced with elimination of methane (Me = CH3, Ph = C6H5): Low valent metals insert into the Si-Si bond of disilanes.

It is widely assumed that these sigma complexes are intermediates in the oxidative addition of hydrosilanes to give metal silyl hydrides.

Oxidative addition of hydrosilane, showing proposed intermediate.
Structure of (MeC 5 H 4 )Mn(CO)(PMe 3 )(η 2 -H 2 SiPh 2 , a sigma complex of diphenylsilane. Selected distances: Si-Mn = 325, H-Fe = 149, Si-H(Mn) = 177, Si-H terminal = 135 picometer . [ 5 ]