Mechanistic aspects of the reactions of nitric oxide with transition-metal complexes.

Trans-effects in octahedral transition metal complexes

Chemistry of nitric oxide relevant to biology.

Department of Chemistry, The Johns Hopkins University, Charles and 34th Streets, Baltimore, Maryland 21218, Kluyver Laboratory for Biotechnology, Delft University of Technology, 2628 BC Delft, The Netherlands, Department of Biochemistry and Molecular Biology, OGI School of Science and Engineering at OHSU, Beaverton, Oregon 97006, and Department of Microbiology and Molecular Genetics, University of California, Los Angeles, California 90095

Nitric Oxide in Biological Denitrification: Fe/Cu Metalloenzyme and Metal Complex NOx Redox Chemistry

Cytochrome c nitrite reductase catalyzes the six-electron reduction of nitrite to ammonia without the release of potential reaction intermediates, such as NO or hydroxylamine. On the basis of the crystallographic observation of reaction intermediates and of density functional calculations, we present a working hypothesis for the reaction mechanism of this multiheme enzyme which carries a novel lysine-coordinated heme group (Fe-Lys). It is proposed that nitrite reduction starts with a heterolytic cleavage of the N−O bond which is facilitated by a pronounced back-bonding interaction of nitrite coordinated through nitrogen to the reduced (Fe(II)) but not the oxidized (Fe(III)) active site iron. This step leads to the formation of an {FeNO}^6 species and a water molecule and is further facilitated by a hydrogen bonding network that induces an electronic asymmetry in the nitrite molecule that weakens one N−O bond and strengthens the other. Subsequently, two rapid one-electron reductions lead to an {FeNO}^8 form and, by protonation, to an Fe(II)−HNO adduct. Hereafter, hydroxylamine will be formed by a consecutive two-electron two-proton step which is dehydrated in the final two-electron reduction step to give ammonia and an additional water molecule. A single electron reduction of the active site closes the catalytic cycle.

Mechanism of the six-electron reduction of nitrite to ammonia by cytochrome c nitrite reductase.

The reaction of the iron(II) picket fence porphyrin derivative [Fe(TpivPP)(NO2)]- (Nasri et al. J. Am. Chem. Soc. 1991, 113, 717) with NO has been examined. The result is a new hexacoordinated iron...

Sharing the π-Bonding. An Iron Porphyrin Derivative with Trans, π-Accepting Axial Ligands. Synthesis, EPR and Mössbauer Spectra, and Molecular Structure of Two Forms of the Complex Nitronitrosyl(α,α,α,α-tetrakis(o-pivalamidophenyl)- porphinato)ferrate(II)

Boi Hanh Huynh, ,§ and

Papers

Sharing the π-Bonding. An Iron Porphyrin Derivative with Trans, π-Accepting Axial Ligands. Synthesis, EPR and Mössbauer Spectra, and Molecular Structure of Two Forms of the Complex Nitronitrosyl(α,α,α,α-tetrakis(o-pivalamidophenyl)- porphinato)ferrate(II)