Synthesis and structures of bimetallic silicon-containing imido alkylidene complexes of tungsten (R′O) 2(ArN)W [dbnd]CH–SiR 2–CH [dbnd]W(NAr)(OR′) 2 (R = Me, Ph) and (R′O) 2(ArN)W [dbnd]CH–SiMe 2SiMe 2–CH [dbnd]W(NAr)(OR′) 2

Abstract

Bimetallic alkylidene complexes of tungsten (R′O) 2(ArN)W CH–SiR 2–CH W(NAr)(OR′) 2 (R = Me ( 1), Ph ( 2)) and (R′O) 2(ArN)W CH–SiMe 2SiMe 2–CH W(NAr)(OR′) 2 ( 3) (Ar = 2 , 6 – Pr 2 i C 6 H 3 ; R′ = CMe 2CF 3) have been prepared by the reactions of divinyl silicon reagents R 2Si(CH CH 2) 2 with known alkylidene compounds R′′–CH Mo(NAr)(OR′) 2. (R′′ = Bu t , PhMe 2C) Complexes 1– 3 were structurally characterized. Ring opening metathesis polymerization (ROMP) of cyclooctene using compounds 1– 3 as initiators led to the formation of high molecular weight polyoctenamers with predominant trans-units content in the case of 1 and 3 and predominant cis-units content in the case of 2.