New dianionic ligands η5-C–5H4Si(Me)2C–(H)SiMe3 and η5-C–5H4SiMe2{NC(But)C(H)SiMe3}–; syntheses, structures and reactivity of their lithium and zirconium derivatives†

Abstract

Lithium and zirconium complexes [Li₂(B)(tmen)]₂ 4, [Li₄(C)₂(tmen)] 5, [Zr(B)₂] 7 and [Zr(C)₂] of the newligands η⁵-C–₅H₄Si(Me)₂C–(H)SiMe₃ ([B]^2–) and η⁵-C–₅H₄Si(Me)₂{NC(Bu^t)C(H)SiMe₃}^– ([C]^2–) are reported, as well as the X-ray structures of the centrosymmetric dimer 4 and of 5 (having each of the four Li atoms in a different environment) and the catalytic activity of 7 for α-alkene polymerisation.