Structural characterization of nitro-substituted phenoxyiminato nickel complexes; inter-molecular π–π interactions in the solid states and effect of the electron drawing groups on catalytic activity

Bis{2-[(2-hydroxy-2-methylpropyl)iminomethyl]-4-nitrophenolato}nickel(II) dimethylformamide monosolvate

“…In the title complex two uninegative tridentate ligands, 5-nitro salicylaldehydene-2,2-dimethyl ethylimine-1-ol, coordinate to the nickel atom producing N 2 O 4 in a slightly distorted octahedral coordination environment. The distortion can be justified by the bond angles formed by the coordinating atoms to the metal: 2Å] as is usually found in such complexes (Ali et al 2006;Butcher et al 1981Butcher et al , 2009Gultneh et al 1998;Mustafaa et al 2009;Zhang et al 2010).…”

Positional Electronic Effects in Iminopyridine‐N‐oxide Nickel Catalyzed Ethylene Polymerization†

“…It is possible that these Lewis basic substituents are poisonous towards the nickel center, leading to decreased activities. [ 52 ] Interestingly, the nickel complexes bearing nitro substituents ( Ni NO , Ni ON , Ni HN , and Ni NN ) resulted in high catalytic activities and produced very high molecular weight polyethylene products (Table 1, entries 11—30), indicating the beneficial effects of the nitro group [ 46‐51 ] and the diarylmethyl moiety. [ 45,52‐54 ]…”

“…[ 3,15,17,43 ] It was shown that some salicylaldimine and α‐diimine nickel catalysts bearing strongly electron‐withdrawing nitro substituent exhibit enhanced catalytic performances, especially the molecular weight of polyethylene. [ 46‐51 ] In this work, a series of dibenzhydryl‐based iminopyridine‐ N ‐oxide ligands bearing a range of electron‐donating or ‐withdrawing substituents (OMe, H, and NO 2 ) and corresponding nickel pre‐catalysts (Chart 1, This work ) were prepared, characterized and investigated in catalytic ethylene polymerization. Specifically, the electronic effect of substitutions at different ligand positions will be studied via installing different substituents at different positions, including 4‐position on the pyridine‐ N ‐oxide moiety (position X ) and 4‐position on the aniline moiety (position Y ).…”

Highly active and easily accessible catalysts for vinyl polymerization of norbornene obtained by oxidative addition of salicylaldimine ligands to bis(1,5‐cyclooctadiene)nickel(0) and methylaluminoxane

“…Ni(cod) 2 (Aldrich) was used as received and stored in the refrigerator in sealed vials under dry argon. Phenoxyimine ligands (DNIPS, NIPS, IPS, and PS) were prepared by the Schiff base condensation of the appropriate aniline and salicylaldehyde derivatives as previously described 25–28…”