CATALYTIC POLYMERIZATION OF PROPYLENE BY HETEROBIMETALLIC BRIDGED EARLY LATE TRANSITION-METAL COMPLEXES/

The polymerization of propylene was studied with a series of dinuclear early transition metal zirconocene-late transition metal complexes br idged by phosphido and arsenide moieties of general formula [(eta(5)-C 5H4R '')(2)Zr{mu-ERR'}(2)M(CO)(n)] (E=P, R=R'=SiMe3, R ''=H, M=Mo, n=4 (1); E=P, R=R'=SiMe3, R ''=H, M=Ni, n=2 (2); E=As, R=R'=SiMe3, R ''=H , M=Cr, n=4 (3); E=P, R=H, R'=2,4,6-i-Pr3C6H2, R ''=Me, M=Mo, n=4 (4); E=P, R=H, R'=2,4,6-i-Pr3C6H2, R ''=Me, M=Cr, n=4 (5)), as well as wit h the corresponding monometallic zirconocene precursor complexes of th e type [(eta(5)-C5H4R '')(2)Zr(ERR')(2)] (E=P, R=R'=SiMe3, R ''=H (6); E=P, R=H, R'=2,4,6-i-Pr3C6H2, R ''=H (7)) and [(eta(5)-C5H4Me)(2)Zr(E RR')Cl] (E=P, R=H, R'=2,4,6-i-Pr3C6H2 (8)). The active cationic specie s were generated treating the complexes with an excess of methylalumox ane (MAO). The catalytic activity was found to be strongly dependent o n temperature and catalyst/MAO ratio. (C) 1998 Elsevier Science B.V.