Organometallic intermediates in the group 4 metallocene-catalyzed dehydrocoupling of organosilanes. 2. Variations in the intermediates of dimethyltitanocene reactions with several silanes

Abstract

As previously described, organosilanes react with dimethyltitanocene (DMT) to give three reduced titanium intermediates, Cp2Ti(μ-SiRR′H)(μ-H)TiCp2, 1, [Cp2Ti(μ-SiRR′H)]2, 2, and [Cp2Ti(H)]2(μ-H), 3. When R = Me and R′ = n-Bu, the DMT is quantitatively converted to 1, which is persistent at room temperature. When R′ = H, DMT is initially converted quantitatively to 1, which then rapidly declines to give an equilibrium mixture of 1, 2, and 3, with 2 as the dominant species. When R = Ph and R′ = Ph or Me, 1 is again produced quantitatively, but it rapidly declines to produce an unidentified paramagnetic product, rather than 2 or 3. It is believed that 2 is unstable with respect to dissociation in these cases due to the steric bulk of the substituents.