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(CH2CH=CHSiR'(3))(2) (R=R'=Me 1; R=Ph, R'=M e 2; R=R'=Ph 3; R=Me, R'=Ph 4; R=Me, R'=Me2But 5) have been prepared by lit hiation of the appropriate 3-silylpropene and quenching with SiCl2R2 (R=Me or Ph). The eta(3)-ansa-bis(allyllithium) compounds [{Li(tmen)}(2){3-(eta(3 )-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'=Me2But 10) complexes were obtained from of the appropriate ans a-bis(propene) and LiBun. The lithium complex 6 was transformed into the po tassium complex [K-2{3-(eta(3)-C3H3SiMe3-1)(2)SiMe2}] 11 and into [Hf{3-(et a(3)-C3H3SiMe3-1)(2)SiMe2}(2)] 13 by reaction with KOBut or HfCl4, respecti vely. From 11 and ZrCl4 [Zr{3-(eta(3)-C3H3SiMe3-1)(2)SiMe2}(2)] 12 was obta ined. Single crystal X-ray structures of complexes 4, 6 and 12 are presente d. Complex 12, in presence of methylaluminoxane (MAO), was an active cataly st for the polymerisation of ethylene.