Substituent Effects in (κ2-N,O)-Salicylaldiminato Nickel(II)−Methyl Pyridine Polymerization Catalysts: Terphenyls Controlling Polyethylene Microstructures

A series of (κ 2 - N, O )-salicylaldiminato Ni(II)−methyl pyridine complexes 7-pyr and 8-pyr derived from 3,5-diiodosalicyaldehyde ( 3a ) and 3-(9-anthryl)salicylaldehyde ( 3b ), and terphenylamines 2,6-(3,5-R-4-R‘-C 6 H 2 ) 2 C 6 H 3 −NH 2 ( 4a, R = CF 3, R‘ = H; 4b, R = t Bu, R‘ = H; 4c, R = t Bu, R‘ = OH; 4d, R = Me, R‘ = H; 4e, R = Me, R‘ = MeO; 4f, R = MeO, R‘ = H; 4g, R = MeO, R‘ = MeO), was prepared by reaction of the respective salicylaldimine ( 5a − f, 6a − g ) with [(tmeda)Ni(CH 3 ) 2 ] (tmeda = N, N, N ‘, N ‘-tetramethylethylenediamine) or [(pyridine) 2 Ni(CH 3 ) 2 ]. Complexes 7-pyr and 8-pyr are highly active single component catalysts for the polymerization of ethylene, producing a wide range of different polyethylene microstructures. While comparable complexes derived from 3a, 3b, 5-nitrosalicylaldehyde, 3- tert -butylsalicylaldehyde, 3,5-[3,5-(CF 3 ) 2 C 6 H 3 ] 2 -salicylaldehyde, and 2,6-[3,5-(CF 3 ) 2 C 6 H 3 ] 2 C 6 H 3 −NH 2 afford polyethylenes with similar degrees of branching, variation of the terphenyl moieties in complexes 7-pyr and 8-pyr allows access to a wide range of polyethylene microstructures under identical reaction conditions. The X-ray diffraction analyses of complexes 7b-pyr and 8f-pyr are reported.