Catalytic diversity of diene complexes of niobium and tantalum on polymerizations of ethylene, norbornene, and methyl methacrylate

摘要

Half-metallocene diene complexes of niobium and tantalum catalyzed three-types of polymerization: (1) the living polymerization of ethylene by niobium and tantalum complexes, MCl2(eta (4)-1,3-diene)(eta (5)-C5R5) (1-4; M = Nb, Ta; R = H, Me) combined with an excess of methylaluminoxane; (2) the stereoselective ring opening metathesis polymerization of norbornene by bis(benzyl) tantalum complexes, Ta(CH2Ph)(2)(eta (4)-1,3-butadiene)(eta (5)-C5R5) (11: R = Me; 12. R = H) and Ta(CH2Ph)(2)(eta (4)-o-xylylene)(eta (5)-C5Me5) (16); and (3) the polymerization of methyl methacrylate by butadiene-diazabutadiene complexes of tantalum, Ta(eta (2)-RN=CHCH=NR)(eta (4)-1,3-butadiene)(eta (5)-C5Me5) (25: R = p-methoxyphenyl; 26: R = cyclohexyl) in the presence of an aluminum compound (24) as an activator of the monomer. [References: 29]