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

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′ = Me2But5) 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′ = Me2But10) 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 KOBut 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.