Synthesis and structural characterisation of new ansa-bis(propene)s and {ansa-bis(allyl)}alkali metal and {ansa-bis(allyl)}transition metal complexes

Abstract

The new ansa-bis(propene)s, R₂Si(CH₂CHCHSiR′₃)₂ (R = R′ = Me 1; R = Ph, R′ = Me 2; R = R′ = Ph 3; R = Me, R′ = Ph 4; R = Me, R′ = Me₂Bu^t5) have been prepared by lithiation of the appropriate 3-silylpropene and quenching with SiCl₂R₂ (R = Me or Ph). The η³-ansa-bis(allyllithium) compounds [{Li(tmen)}₂{3-(η³-C₃H₃SiR′₃-1)₂}SiR₂] (R = R′ = Me 6; R = Ph, R′ = Me 7; R = R′ = Ph 8; R = Me, R′ = Ph 9; R = Me, R′ = Me₂Bu^t10) complexes were obtained from of the appropriate ansa-bis(propene) and LiBuⁿ. The lithium complex 6 was transformed into the potassium complex [K₂{3-(η³-C₃H₃SiMe₃-1)₂SiMe₂}] 11 and into [Hf{3-(η³-C₃H₃SiMe₃-1)₂SiMe₂}₂] 13 by reaction with KOBu^t or HfCl₄, respectively. From 11 and ZrCl₄ [Zr{3-(η³-C₃H₃SiMe₃-1)₂SiMe₂}₂] 12 was obtained. Single crystal X-ray structures of complexes 4, 6 and 12 are presented. Complex 12, in presence of methylaluminoxane (MAO), was an active catalyst for the polymerisation of ethylene.