[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)]⁺ (<b>IV</b>), the product of a single 1,2-insertion of TEVS into the Ti-Me bond. On heating, complex <b>IV</b> undergoes a CH bond activation process to give the isomeric species [Cp₂TiCH₂CH₂(SiEt₂CHMe₂)]⁺ (<b>V</b>) in which a Ti–C­(β) interaction (Ti←C­(β)-Si) is facilitated by an unusual γ-silyl effect. The structures of <b>IV</b> and <b>V</b> 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