Characterization of A New Copper(I)−Nitrito Complex That Evolves Nitric Oxide

The complexes [Cu(κ2-Ph2PC6H4(o-OMe))2(CH3CN)](BF4) (1) and [CuCl(Ph2PC6H4(o-OMe))2] (2) have been prepared by treating [Cu(CH3CN)4](BF4) or CuCl with two equivalents o-(diphenylphosphino)anisole (Ph2PC6H4(o-OMe)) at room temperature, respectively. The reaction of 1 and (PPN)(NO2) in acetonitrile solution affords a neutral compound [Cu(Ph2PC6H4(o-OMe))2(ONO)] (3). In contrast to the synthesis of 3, mixing NaNO2 and 1 in MeOH yielded a unique dicopper(I) cationic species, [((Ph2PC6H4(o-OMe))2Cu)2(μ-NO2)]+ (4) after ether/CH2Cl2 crystallization. The molecular structures of 1−4 have been determined by an X-ray diffraction study. The copper(I)−nitrito adduct 3 containing phosphine−ether ligands forms nitric oxide gas from the reaction with acetic acid, suggesting the first example and model compound in the asymmetric O-bound copper(I) nitrite intermediate microenvironment of copper nitrite reductases (Cu-NIRs).