title: Reactions of a heme-superoxo complex toward a cuprous chelate and •NO(g): CcO and NOD chemistry.
abstract: Following up on the characterization of a new (heme)FeIII-superoxide species formed from the cryogenic oxygenation of a ferrous-heme (PPy)FeII(1) (PPy= a tetraarylporphyrinate with a covalently tethered pyridine group as a potential axial base), giving (PPy)FeIII-O2•-(2) (Li Y et al., Polyhedron2013;58: 60-64), we report here on (i) its use in forming a cytochromecoxidase (CcO) model compound, or (ii) in a reaction with nitrogen monoxide (•NO; nitric oxide) to mimic nitric oxide dioxygenase (NOD) chemistry. Reaction of (2) with the cuprous chelate [CuI(AN)][B(C6F5)4] (AN = bis[3-(dimethylamino) propyl]amine) gives ameta-stable product [(PPy)FeIII-([Formula: see text])-CuII(AN)][B(C6F5)4] (3a), possessing a high-spin iron(III) and Cu(II) side-on bridged peroxo moiety with a μ-η2:η2-binding motif. This complex thermally decays to a corresponding μ-oxo complex [(PPy)FeIII-(O2-)-CuII(AN)][B(C6F5)4] (3). Both (3) and (3a) have been characterized by UV-vis,2H NMR and EPR spectroscopies. When (2) is exposed to •NO(g), a ferric heme nitrato compound forms; if 2,4-di-tert-butylphenol is added prior to •NO(g)exposure, phenolortho-nitration occurs with the iron product being the ferric hydroxide complex (PPy) FeIII(OH) (5). The latter reactions mimic the action of NOD's.
authors.affiliation: Department of Chemistry, Johns Hopkins University, Baltimore, MD 21218, USA.
authors.forename: Savita K
authors.initials: SK
authors.lastname: Sharma
authors.affiliation: Department of Chemistry, Johns Hopkins University, Baltimore, MD 21218, USA.
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Rogler
authors.affiliation: Department of Chemistry, Johns Hopkins University, Baltimore, MD 21218, USA.
authors.forename: Kenneth D
authors.initials: KD
authors.lastname: Karlin
keywords: heme-copper-μ-oxo; heme-superoxo; high spin heme-copper peroxo; nitrate; peroxynitrite