Homo- and Co-Polymerization of Ethylene with Cyclic Olefins Catalyzed by Phosphine Adducts of (Imido)vanadium(IV) Complexes

Abstract

The synthesis and the characterization of a series of phosphine adducts of (imido)vanadium(IV) dichloride complexes of the type V(═NR)Cl2(PMe2Ph)2 [R = 2,6-Cl2-Ph (1), 2,6-iPr2-Ph (2), and tBu (3)] and V(═NtBu)Cl2(PMe3)2 (3′) are reported. The solid-state structures of 1 and 3′ were determined by X-ray crystallography. The complexes present a geometry around the metal center between a distorted trigonal-bipyramid and a square pyramid, with an almost linear N–V–C bond. Complexes 1–3 were evaluated as catalyst precursors for the polymerization of ethylene and ethylene copolymerization with various cyclic olefins (i.e., norbornene, dicyclopentadiene, 5-ethylidene-2-norbornene, and 5-vinyl-2-norbornene). In combination with Et2AlCl (500 equiv to V) and Cl3CCO2Et (ETA, 10 equiv to V), 1–3 are versatile and promising catalysts for the synthesis of high molecular weight linear poly(ethylene)s and alternating copolymers with efficient comonomer incorporation, unimodal molecular weight distributions, and uniform c...