Nickel(<scp>ii</scp>) complexes of a 3N ligand as a model for diketone cleaving unusual nickel(<scp>ii</scp>)-dioxygenase enzymes

Abstract

Diketone substrate bound nickel(ii) complexes of 2,6-bis(1-methylbenzimidazolyl)pyridine have been synthesized and characterized as relevant active site models for unusual diketone cleaving Ni(ii)-dependent enzymes Ni-ARD and DKDO. The average Ni-N_py/benzim bond distances (2.050-2.107 Å) of model complexes are almost identical to the Ni-N_His bond distances of Ni^II-ARD (2.02-2.19 Å). The reaction of these adducts with dioxygen exhibited C-C cleavage with the rate of k_O₂, 5.24-73.71 × 10^-3 M^-1 s^-1. The phenyl substituted adduct regioselectively elicits 52% of benzoic acid as the major product.