The formation and structures of the methyl-bridged complexes Cp*TiMe2(μ,-Me) B(C6F5)3 and [Cp*TiMe2(μ-Me) TiMe2Cp * ][MeB( C6F5) 3]

Article abstract of DOI:10.1016/S0022-328X(96)06622-3

Reaction of the compound Cp*TiMe₃ (Cp * = η⁵-pentamethylcyclopentadienyl) with the potent Lewis acid B(C₆F₅)₃ results in methyl carbanion abstraction from the titanium and formation of the corresponding complex Cp*TiMe2(μ-Me)B(C₆F₅)₃, in which a methyl group bridges the titanium and boron atoms. The isotopically labelled compounds Cp*Ti(CH₂D)₃, Cp*Ti(CH₂D)₂(μ-CH₂D)B(C₆F₅)₃, Cp*Ti(¹³CH₃)₃, and Cp*Ti(¹³CH₃)₂(μ-¹³CH₃)B(C₆F₅)₃ have also been prepared to provide NMR probes of the possibility of α-agostic bonding in these compounds, and while the answer appears to be 'no', a caveat on the use of this type of experiment is proposed. The compounds Cp*TiMe₃ and Cp*TiMe₂(μ-Me)B(C₆F₅)₃ react further to form the novel but unstable methyl-bridged species [Cp*TiMe₂(μ-Me)TiMe₂Cp*][MeB(C₆F₅)₃], which has been characterized by ¹H and ¹³C{¹H} NMR spectroscopy.