Remarkably Active Non-Metallocene Ethylene Polymerization Catalysts

The bis(tri- tert -butylphosphinimide) complexes ( t -Bu 3 PN) 2 TiCl 2 ( 1 ) and ( t -Bu 3 PN) 2 TiMe 2 ( 2 ) were prepared and characterized crystallographically. Stoichiometric reactions of 2 with PhNMe 2 H[B(C 6 F 5 ) 4 ] in the presence of PMe 3 afforded [( t -Bu 3 PN) 2 TiMe(PMe 3 )][B(C 6 F 5 ) 4 ] ( 3 ), while reaction of 2 with B(C 6 F 5 ) 3 affords ( t -Bu 3 PN) 2 TiMe(μ-Me)B(C 6 F 5 ) 3 ( 4 ). Under laboratory conditions these compounds are effective ethylene polymerization catalysts. Under commercially relevant solution polymerization conditions, these catalysts are exceptionally active. Complex 2, when activated with Ph 3 C[B(C 6 F 5 ) 4 ], produces high molecular weight polyethylene with a narrow polydispersity at a rate approximately 4 times faster than the constrained geometry catalyst ((C 5 Me 4 SiMe 2 N- t -Bu)TiX 2 ). As such, these catalysts represent the first non-cyclopentadienyl, single-site catalysts competitive with derivatives of metallocenes under commercially relevant polymerization conditions.