Reaction of a Redox-Active Ligand Complex of Nickel with Dioxygen Probes Ligand-Radical Character

Abstract

(Chemical Equation Presented) Bis(imino)pyridine complex [Ni{2,6-(ArN=CMe)2C5H3N}Cl] (where Ar = 2,6-iPr2C6H3) was synthesized by reduction of the corresponding dichloride complex and characterized as a ligand-radical complex of NiII. Reaction of this complex with O 2 caused intraligand C-C bond cleavage to afford the Ni complex of the new iminoethylpyridylcarboxamidato ligand, which also was isolated as the corresponding carboxamide, 6-(ArN=CMe)C5H3N-2-C(O)NHAr. This reaction serves as an example of small-molecule activation effected directly at the redoxactive bis(imino)pyridine ligand without an overall oxidation state change at the Ni center.