[Cp2TiCH2CH2(SiEt2CHMe2)]+, an Alkyl-titanocene(IV) Complex Containing an Unconventional Ti←C(β)-Si Mode of Bonding

The compound [Cp2Ti(Me)(CD2Cl2)][B(C6F5)4] reacts with triethylvinylsilane (TEVS) to give the γ-agostic σ-alkyl complex [Cp2TiCH2CHMe(SiEt3)]+ (IV), the product of a single 1,2-insertion of TEVS into the Ti-Me bond. On heating, complex IV undergoes a CH bond activation process to give the isomeric species [Cp2TiCH2CH2(SiEt2CHMe2)]+ (V) in which a Ti−C(β) interaction (Ti←C(β)-Si) is facilitated by an unusual γ-silyl effect. The structures of IV and V and the nature of the isomerization process were explored by DFT methods which suggest that isomerization proceeds via an intramolecular 1,5-σ bond metathesis reaction which involves ε-agostic interactions.