A stable hyponitrite-bridged iron porphyrin complex

The coupling of two nitric oxide (NO) molecules in heme active sites is an important contributor to the conversion of NO to nitrous oxide (N ₂O) by heme-containing enzymes. Several formulations for the presumed heme-Fe{N ₂O ₂}n- intermediates have been proposed previously, however, no crystal structures of heme-Fe{N ₂O ₂}n- systems have been reported to date. We report the first isolation and characterization of a stable bimetallic hyponitrite iron porphyrin, [(OEP)Fe]2(μ-N ₂O ₂), prepared from the reaction of [(OEP)Fe] ₂(μ-O) with hyponitrous acid. Density functional theoretical calculations were performed on the model compound [(porphine)Fe] ₂(μ-N ₂O ₂) to characterize its electronic structure and properties.