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

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-Npy/benzim bond distances (2.050-2.107 Å) of model complexes are almost identical to the Ni-NHis bond distances of NiII-ARD (2.02-2.19 Å). The reaction of these adducts with dioxygen exhibited C-C cleavage with the rate of kO2, 5.24-73.71 × 10-3 M-1 s-1. The phenyl substituted adduct regioselectively elicits 52% of benzoic acid as the major product.