Reactions of a silyl(silylene)iron complex with nitriles: Carbon-carbon bond cleavage of nitriles by the transiently generated disilanyliron(II) intermediate

A silyl(silylene) iron complex, Cp*Fe(CO)(=SiMes₂) SiMe₃ (1), which was prepared by the photoreaction of Cp*Fe(CO)₂Me (2) with hydrodisilane Mes ₂MeSiSiMe₂H (3), reacted with nitriles RCN (R = Ph, Me) at 80°C to afford a mixture of a disilanyl isocyanide complex Cp*Fe(CO)(R)(CNSiMe₂SiMes₂Me) (5a, R = Ph; 5b, R = Me) and a pair of diastereomers of Cp*Fe(CO)(R)(CNSiMesMeSiMesMe ₂) (6a, R = Ph; 6b, R = Me). The molecular structure of 5a was determined by X-ray crystallography. On the other hand, when the photoreaction of 2 with 3 was performed in the presence of benzonitrile, acetonitrile, or acetonitrile-d₃, at ca. 5°C, only the disilanyl isocyanide complex 5a, 5b, or 5b-d₃ was obtained as a single product. The formation of these disilanyl isocyanide complexes is understood by the action of coordinatively unsaturated disilanyliron(II) intermediates Cp*Fe(CO) SiMe₂SiMes₂Me, etc., which are transiently generated by thermal isomerization of 1 or photoreaction of 2 with 3, to incoming nitriles. The C-C bond of the nitrile ligand is activated through migration of the disilanyl group to the nitrogen atom of nitriles.