New ring-opening metathesis polymerization catalyst based on a five-coordinate tungsten(VI) alkylidene complex containing an ortho-chelating arylamine ligand; X-ray structure of [W{C6H4(CH2NMe2)-2}(NPh)(CHSiMe3)(CH2SiMe3)]

Abstract

At –78°C [W(NPh)(CH₂SiMe₃)₃Cl] reacts with 2-[(dimethylamino)methyl]phenyllithium in diethyl ether to produce a tetra-organotungsten(VI) complex which decomposes by an H_α-elimination reaction generating a novel tungsten(VI) alkylidene with intramolecular coordination of an amine function; this complex reacts with norbornene to provide a cis-polymer that is the result of a selective ring-opening metathesis.