Dichlorovanadium(IV) diamine-bis(phenolate) complexes for ethylene (co)polymerization and 1-olefin isospecific polymerization

Abstract Two vanadium complexes bearing amine-bis(phenolate) ligands with the amino side-arm donor, [V{Me 2 NCH 2 CH 2 N(CH 2 -2-O-3,5- t Bu 2 -C 6 H 2 ) 2 }Cl 2 ] ( 1 ) and [V{Me 2 NCH 2 CH 2 N(CH 2 -2-O-3,5- t Bu 2 -C 6 H 2 )(CH 2 -2-O-C 6 H 4 )}Cl 2 ] ( 2 ), were synthesised and characterized by FTIR and 1 H NMR spectroscopy. Upon activation with Al( i Bu) 3 /Ph 3 CB(C 6 F 5 ) 4 , these complexes became active catalysts for 1-octene polymerization giving highly stereoregular polymers ( mmmm  ∼ 90%) having regioirregularly arranged units. The catalytic activity of the catalysts in ethylene homo- and copolymerization, and their ability to incorporate a comonomer were highly dependent on both the activator type and the complex structure. 1 /EtAlCl 2 exhibited very high activity (up to 3.3 · 10 7  g/(mol V  h)) in ethylene polymerization and produced copolymers with the highest comonomer content (up to 9.1 mol%), moderate molecular weight and narrow chemical composition distribution (CCD). Both vanadium complexes, when combined with trityl borate activator, led to ethylene copolymers with lower 1-octene content and broad CCD. In addition, the copolymers were characterized by very high molecular weight (∼1 · 10 6  g/mol) and narrow dispersity (M w /M n  = 1.4–2.0).