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
posted on 2002-01-30, 00:00authored byKotohiro Nomura, Asami Sagara, Yukio Imanishi
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 2b (3700−8300 kg of PE/mol of V h) have also been observed for ethylene
polymerization in the presence of Et2AlCl, which was an ineffective cocatalyst for the above ROMP.