Facile access to silicon-functionalized bis-silylene titanium(II) complexes.

A series of unprecedented bis-silylene titanium(II) complexes of the type [(η(5)-C(5)H(5))(2)Ti(LSiX)(2)] (L=PhC(NtBu)(2); X=Cl, CH(3), H) has been prepared using a phosphane elimination strategy. Treatment of the [(η(5)-C(5)H(5))(2)Ti(PMe(3))(2)] precursor (1) with two molar equivalents of the N-heterocyclic chlorosilylene LSiCl (2), results in [(η(5)-C(5)H(5))(2)Ti(LSiCl)(2)] (3) with concomitant PMe(3) elimination. The presence of a Si-Cl bond in 3 enabled further functionalization at the silicon(II) center. Accordingly, a salt metathesis reaction of 3 with two equivalents of MeLi results in [(η(5)-C(5)H(5))(2)Ti(LSiMe)(2)] (4). Similarly, the reaction of 3 with two equivalents of LiBHEt(3) results in [(η(5)-C(5)H(5))(2)Ti(LSiH)(2)] (5), which represents the first example of a bis-(hydridosilylene) metal complex. All complexes were fully characterized and the structures of 3 and 4 elucidated by single-crystal X-ray diffraction analysis. DFT calculations of complexes 3-5 were also carried out to assess the nature of the titanium-silicon bonds. Two σ and one π-type molecular orbital, delocalized over the Si-Ti-Si framework, are observed.