Remote control: Substituents strongly affect the catalytic properties of complexes 1 in ethylene polymerization, despite their remoteness from the active center. An appropriate substitution pattern provides very active and robust catalysts.

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,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-tertbutylsalicylaldehyde, 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.

Ethylene/norbornene and ethylene/1-butene copolymerization with nickel(II) salicylaldiminato complexes [{κ2-N,O-6-C(H)N(2,6-R2C6H3)-2,4-R‘2C6H2O}NiMe(pyridine)] (1a, R = 3,5-Me2C6H3, R‘ = I; 1b, R,R‘ = 3,5-(F3C)2C6H3; 1c, R = 3,5-(F3C)2C6H3, R‘ = I; 2, R = iPr, R‘ = I) were studied in toluene as a reaction medium and in emulsion, the latter affording polymer dispersions. High molecular weight copolymers (M n > 104 g mol-1) are formed. Incorporation of ethylene is much preferred over butene incorporation, X Bu/x Bu ∼0.05 under typical reaction conditions, by comparison incorporation of the strained olefin norbornene is higher, X NB/x NB ∼0.25 (X = comonomer mole fraction in polymer; x = comonomer mole fraction in reaction mixture). Dispersions contained copolymers with up to 6 mol % comonomer (12 wt % for 1-butene; 20 wt % for norbornene). Incorporation of a few mol % of norbornene strongly decreases polymer crystallinity, which enhances the film forming properties of dispersions. Microstructure analysis by 13C NMR shows that butene is incorporated in a 1,2-, 1,3- and 1,4-fashion. Whether 1,2- or 1,3-incorporation is predominant depends on the catalyst (nature of R).

A series of new binuclear neutral κ2-N,O-chelated Ni(II) complexes [(H2C) n {[(2,6-R2-4-yl-C6H2)-NC(H)-(3,5-I2-2-O-C6H2)-κ2-N,O]Ni(CH3)(pyridine)}2] (R = iPr, 3,5-(CF3)2C6H3; n = 0, 1) are reported. The complexes are single-component catalyst precursors for ethylene polymerization. Catalyst activities exceed those of mononuclear analogues studied substantially. With 3.4 × 105 TO h−1, high molecular weight polymer is obtained (M w 9.2 × 105 g mol−1; M n 2.8 × 105 g mol−1). Semicrystalline polyethylene with a low degree of branching is formed (2 to 12 branches/1000 carbon atoms; prepared at 30 to 70 °C polymerization temperature), with T m 112 to 136 °C. Polymerization in aqueous emulsion affords polyethylene dispersions.