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Updated: May 23, 2026

Ethylene Polymerizations Using Parallel Pressure Reactors and a Kinetic Analysis of Chain Transfer Polymerization
Published on: November 27, 2015
Dinuclear Group 4 Metallocene Catalysts of the Type [(Cp2M)2(μ-Me)(μ-C2R)]: Structure-Activity Relationships in
Hanan Al Hamwi1, Mirko Rippke1, Anke Spannenberg1
1Leibniz Institute for Catalysis, Rostock, Germany.
Abstract:
The heterodinuclear zirconocene/titanocene complexes, [Cp2Zr(μ-Me)(μ-C2R)(TiCp2)] where R = SiMe3 and R = Ph, were prepared using the previously reported comproportion reaction of the zirconocene alkynyl methyl complex with Rosenthal's zirconocene source. Examination of the molecular structure revealed alkynyl group migration from Zr to Ti, as confirmed by single-crystal x-ray analysis, nuclear magnetic resonance spectroscopy, and quantum chemical calculations. The homodinuclear (Zr/Zr) and heterodinuclear (Ti/Zr) complexes were activated with [Ph3C][B(C6F5)4], B(C6F5)3, and a mixture of B(C6F5)3 with excess Et3SiH (SiHB system) as aluminium-free activators and tested in ethylene polymerization. Depending on the type of activator, unique reactivity was observed, resulting in either electron or methyl abstraction and the formation of cationic species. The catalytically active species are proposed to have dinuclear character, forming linear polyethylenes with unsaturated groups predominantly on the Zr cationic center. In contrast, the Ti cationic center generated by a SiHB system only in dichloromethane produced silicon-terminated polyethylenes.
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