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