Olefin Polymerization and Ring-Opening Metathesis Polymerization of Norbornene by (Arylimido)(aryloxo)vanadium(V) Complexes of the Type VX2(NAr)(OAr‘). Remarkable Effect of Aluminum Cocatalyst for the Coordination and Insertion and Ring-Opening Metathesis Polymerization

Abstract

Various (arylimido)(aryloxo)vanadium(V) complexes of the type VCl2(NAr)(OAr‘) [NAr = N-2,6-Me2C6H3 (2), N-2,6-iPr2C6H3 (3); OAr‘ = O-2,6-Me2C6H3 (a), O-2,6-iPr2C6H3 (b), O-2,6-tBu2-4-MeC6H2 (c)] have been prepared in high yields from VCl3(NAr) with Ar‘OH in n-hexane. 2b exhibited remarkable catalytic activity for ethylene polymerization in the presence of methylaluminoxane (MAO), affording high molecular weight polymer with unimodal molecular weight distribution (Mw = 2.92 × 106, Mw/Mn = 2.88). V(CH2Ph)2(N-2,6-Me2C6H3)(O-2,6-iPr2C6H3) (4) initiated ring-opening metathesis polymerization (ROMP) of norbornene without cocatalyst, affording high molecular weight polymer with unimodal molecular weight distribution (Mw = 4.69 × 106, Mw/Mn = 1.93). The ROMP also proceeded efficiently if 2b or 2c was treated with AlMe3 (5−10 equiv) in toluene, and high stereoregularity (trans/cis = 91/9) in the olefinic double bond for the resultant polymer was observed by 2b. On the other hand, remarkable catalytic activities by...