Synthesis and Reactivity of Alkenyl‐Substituted Zirconocene Complexes and Their Application as Olefin Polymerisation Catalysts

Abstract

AbstractThe zirconocene complexes [Zr(η5‐C5H5){η5‐C5H4(CMe2CH2CH2CH=CH2)}Cl2] (4) and [Zr{η5‐C5H4(CMe2CH2CH2CH=CH2)}2Cl2] (5) were synthesised from the reaction of the lithium derivative [Li{C5H4(CMe2CH2CH2CH=CH2)}] (1) with [Zr(η5‐C5H5)Cl3] or ZrCl4, respectively. The ansa‐zirconocene complex [Zr{Me2Si(η5‐C5Me4)(η5‐C5H3{CMe2CH2CH2CH=CH2})}Cl2] (6) was obtained from the reaction of the lithium precursor [Li2{Me2Si(η5‐C5Me4)(η5‐C5H3{CMe2CH2CH2CH=CH2})}] (3) with zirconium tetrachloride. Catalytic hydrogenation of 4–6 gave the zirconocene complexes [Zr(η5‐C5H5){η5‐C5H4(CMe2CH2CH2CH2CH3)}Cl2] (7), [Zr{η5‐C5H4(CMe2CH2CH2CH2CH3)}2Cl2] (8) and [Zr{Me2Si(η5‐C5Me4)(η5‐C5H3{CMe2CH2CH2CH2CH3})}Cl2] (9), respectively. Hydroboration of 4–6 with 9‐BBN (9‐borabicyclo[3.3.1]nonane) yielded [Zr(η5‐C5H5){η5‐C5H4(CMe2CH2CH2CH2CH2BC8H14)}Cl2] (10), [Zr{η5‐C5H4(CMe2CH2CH2CH2CH2BC8H14)}2Cl2] (11) and[Zr{Me2Si(η5‐C5Me4)(η5‐C5H3{CMe2CH2CH2CH2CH2BC8H14})}Cl2] (12), respectively, and the catalytic hydrosilylation of 4–6 with SiHMe2Cl gave [Zr(η5‐C5H5){η5‐C5H4(CMe2CH2CH2CH2CH2SiMe2Cl)}Cl2] (13), [Zr{η5‐C5H4(CMe2CH2CH2CH2CH2SiMe2Cl)}2Cl2] (14) and [Zr{Me2Si(η5‐C5Me4)(η5‐C5H3{CMe2CH2CH2CH2CH2SiMe2Cl})}Cl2] (15), respectively. The dinuclear complex [Cl2Zr{Me2Si(η5‐C5Me4)(η5‐C5H3{CMe2(CH2)4SiMe2OSiMe2(CH2)4Me2C}η5‐C5H3)(η5‐C5Me4)SiMe2}ZrCl2] (16) was obtained upon controlled hydrolysis of 15. The zirconocene compounds were tested as catalysts in the polymerisation of ethylene and propylene. Isotactic polypropylene with [mmmm] pentads of the order of 75 % were obtained with the ansa‐zirconocene catalysts, whereas the unbridged metallocene catalysts produced atactic polypropylene. The molecular structures of 4 and 5 were determined by single‐crystal X‐ray diffraction studies.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)