title: Chromium(IV)-peroxo complex formation and its nitric oxide dioxygenase reactivity.
abstract: The O(2) and NO reactivity of a Cr(II) complex bearing a 12-membered tetraazamacrocyclic N-tetramethylated cyclam (TMC) ligand, [Cr(II)(12-TMC)(Cl)](+) (1), and the NO reactivity of its peroxo derivative, [Cr(IV)(12-TMC)(O(2))(Cl)](+) (2), are described. By contrast to the previously reported Cr(III)-superoxo complex, [Cr(III)(14-TMC)(O(2))(Cl)](+), the Cr(IV)-peroxo complex 2 is formed in the reaction of 1 and O(2). Full spectroscopic and X-ray analysis revealed that 2 possesses side-on η(2)-peroxo ligation. The quantitative reaction of 2 with NO affords a reduction in Cr oxidation state, producing a Cr(III)-nitrato complex, [Cr(III)(12-TMC)(NO(3))(Cl)](+) (3). The latter is suggested to form via a Cr(III)-peroxynitrite intermediate. [Cr(II)(12-TMC)(NO)(Cl)](+) (4), a Cr(II)-nitrosyl complex derived from 1 and NO, could also be synthesized; however, it does not react with O(2).
authors.affiliation: Department of Bioinspired Science, Ewha Womans University, Seoul 120-750, Korea.
authors.forename: Atsutoshi
authors.initials: A
authors.lastname: Yokoyama
authors.forename: Jung Eun
authors.initials: JE
authors.lastname: Han
authors.forename: Jaeheung
authors.initials: J
authors.lastname: Cho
authors.forename: Minoru
authors.initials: M
authors.lastname: Kubo
authors.forename: Takashi
authors.initials: T
authors.lastname: Ogura
authors.forename: Maxime A
authors.initials: MA
authors.lastname: Siegler
authors.forename: Kenneth D
authors.initials: KD
authors.lastname: Karlin
authors.forename: Wonwoo
authors.initials: W
authors.lastname: Nam
mesh_terms: D002857:Chromium / Q000737:chemistry*; D008958:Models, Molecular; D010084:Oxidation-Reduction; D010105:Oxygenases / Q000737:chemistry*; D010545:Peroxides / Q000737:chemistry*
chemical_list: D010545:Peroxides; D002857:Chromium; D010105:Oxygenases; C114415:nitric oxide dioxygenase