Nitric Oxide Oxidation Mediated by Substituted Nickel Phthalocyanines: A Theoretical Viewpoint

The oxidation of nitric oxide (NO) mediated by substituted nickel phthalocyanines (NiPc(X) n) has been investigated for 19 complexes at the B3LYP and M05-2X/LANL2DZ/6-31G(d) levels of theory. Unimolecular reactivity descriptors like chemical potential and electrophilicity were calculated for NiPc(X) n, giving an account of the substituent effect and indicating that electron-withdrawing groups favor the reduction of NiPc(X) n. Bimolecular reactivity descriptor as donor-acceptor hardness was used to get information about the affinity of NO by NiPc(X) n and suggests that Ni(III) has better affinity than Ni(II). A mechanism where Ni(III) catalyzes the oxidation of NO instead of Ni(II) was proposed. Optimized molecular structures calculated for the NO?NiPc(X) n adducts confirm that a larger charge transfer occurs from NO to Ni(III)Pc(X) n in comparison with Ni(II)Pc(X) n and that the reduction in the former complexes happens on the phthalocyanine ligand. © 2012 American Chemical Society.