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

Chuang, Wan‐Jung; Lin, I-Jung; Chen, Hsing-Yin; Chang, Yu‐Lun; Hsu, Sodio C. N.

doi:10.1021/ic100083b

Cited by 37 publications

(26 citation statements)

References 44 publications

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“…On the basis of previous studies of symmetric N , N ′-alkyl- or N , N ′-aryl-substituted β-diketiminato copper complexes and our previous work on biomimetic copper complexes, − we decided to vary the ligand framework to probe new binding motifs and reactivity in copper chemistry. β-Diketiminato copper(I) complexes were synthesized by replacing the symmetric N , N ′-alkyl- or N , N ′-aryl-substituted ligands with unsymmetrical N -aryl- N ′-alkyl-substituted ligands .…”

Section: Introductionmentioning

confidence: 99%

Reactivity Study of Unsymmetrical β-Diketiminato Copper(I) Complexes: Effect of the Chelating Ring

et al. 2017

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β-Diketiminato copper(I) complexes play important roles in bioinspired catalytic chemistry and in applications to the materials industry. However, it has been observed that these complexes are very susceptible to disproportionation. Coordinating solvents or Lewis bases are typically used to prevent disproportionation and to block the coordination sites of the copper(I) center from further decomposition. Here, we incorporate this coordination protection directly into the molecule in order to increase the stability and reactivity of these complexes and to discover new copper(I) binding motifs. Here we describe the synthesis, structural characterization, and reactivity of a series of unsymmetrical N-aryl-N'-alkylpyridyl β-diketiminato copper(I) complexes and discuss the structures and reactivity of these complexes with respect to the length of the pyridyl arm. All of the aforementioned unsymmetrical ß-diketiminato copper(I) complexes bind CO reversibly and are stable to disproportionation. The binding ability of CO and the rate of pyridyl ligand decoordination of these copper(I) complexes are directly related to the competition between the degree of puckering of the chelate system and the steric demands of the N-aryl substituent.

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Section: Introductionmentioning

confidence: 99%

Reactivity Study of Unsymmetrical β-Diketiminato Copper(I) Complexes: Effect of the Chelating Ring

et al. 2017

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“…2.8 Å) and aligns the two Cu d x 2 – y 2 orbitals with the nitrite π* orbital in the μ–η 2 :η 2 -NO 2 binding mode, which weakens the ON–O bond in NO 2 – . While the μ–η 2 :η 2 -NO 2 binding mode is also possible with mononuclear analog 3 , the commonly observed μ–η 1 :κ 2 -NO 2 binding mode is perhaps more favorable, ,, since it allows the soft Cu(I) to interact with the N atom and the hard Cu(II) to interact with O atoms. Since the otherwise favored μ–η 1 :κ 2 -NO 2 binding mode requires an intermetallic distance of at least 4.3 Å, ,, the binuclear L prevents the formation of the inactive μ–η 1 :κ 2 -NO 2 sink, therefore making the O–NO bond cleavage reactivity somewhat unique to the linked bimetallic system.…”

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confidence: 99%

Dicopper μ-Oxo, μ-Nitrosyl Complex from the Activation of NO or Nitrite at a Dicopper Center

et al. 2019

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Treatment of a dicopper(I,I) complex with nitric oxide produces a dicopper μ-oxo, μ-nitrosyl complex [LCu2(μ-O)(μ-NO)]2+, representing the first structurally characterized μ-oxo, μ-nitrosyl metal complex. This compound can also be synthesized from the reaction of nitrite with an [LCuIICuI]3+ synthon. Full characterization of the thermal-sensitive [LCu2(μ-O)(μ-NO)]2+ complex with IR, EPR, and X-ray crystallography suggests a localized mixed-valent CuIII, CuII, O2–, NO– formulation. The [Cu2(μ-O)(μ-NO)]2+ core efficiently oxidizes exogenous substrates, such as phosphine, cyclohexadienes, and isochroman to afford phosphine oxide, benzene, and 1-isochromanone. Since both nitrite and nitric oxide are proposed oxidants in denitrifying methane oxidation, the oxidative reactivity of [Cu2(μ-O)(μ-NO)]2+ core is potentially relevant to anaerobic methane oxidation observed in methanotrophic archaea.

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“…Then, for steric reasons it is expected a substituted enzyme mechanism without accumulation of ternary complex, implying that nitrite should bind T2 in its Cu + state. There are some examples in the literature of Cu(I) and Cu(II) complexes which can reduce nitrite to NO [59,60]. The reduction of nitrite in a Cu + site might explain the low turnover number observed in C172D relative to that of wt SmNir, since T2(Cu + )-nitrite interaction is electrostatically less favorable than that for T2(Cu 2+ )-nitrite complex.…”

Section: Kinetic Assays Using MV and Smpaz As Electron Donorsmentioning

confidence: 99%

Study of the Cys-His bridge electron transfer pathway in a copper-containing nitrite reductase by site-directed mutagenesis, spectroscopic, and computational methods

Cristaldi

Gómez

González

et al. 2018

Biochimica et Biophysica Acta (BBA) - General Subjects

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The Cys-His bridge as electron transfer conduit in the enzymatic catalysis of nitrite to nitric oxide by nitrite reductase from Sinorhizobium meliloti 2011 (SmNir) was evaluated by site-directed mutagenesis, steady state kinetic studies, UV-vis and EPR spectroscopic measurements as well as computational calculations. The kinetic, structural and spectroscopic properties of the His171Asp (H171D) and Cys172Asp (C172D) SmNir variants were compared with the wild type enzyme. Molecular properties of H171D and C172D indicate that these point mutations have not visible effects on the quaternary structure of SmNir. Both variants are catalytically incompetent using the physiological electron donor pseudoazurin, though C172D presents catalytic activity with the artificial electron donor methyl viologen (k=3.9(4) s) lower than that of wt SmNir (k=240(50) s). QM/MM calculations indicate that the lack of activity of H171D may be ascribed to the NH…OC hydrogen bond that partially shortcuts the T1-T2 bridging Cys-His covalent pathway. The role of the NH…OC hydrogen bond in the pH-dependent catalytic activity of wt SmNir is also analyzed by monitoring the T1 and T2 oxidation states at the end of the catalytic reaction of wt SmNir at pH6 and 10 by UV-vis and EPR spectroscopies. These data provide insight into how changes in Cys-His bridge interrupts the electron transfer between T1 and T2 and how the pH-dependent catalytic activity of the enzyme are related to pH-dependent structural modifications of the T1-T2 bridging chemical pathway.

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

Cited by 37 publications

References 44 publications

Reactivity Study of Unsymmetrical β-Diketiminato Copper(I) Complexes: Effect of the Chelating Ring

Reactivity Study of Unsymmetrical β-Diketiminato Copper(I) Complexes: Effect of the Chelating Ring

Dicopper μ-Oxo, μ-Nitrosyl Complex from the Activation of NO or Nitrite at a Dicopper Center

Study of the Cys-His bridge electron transfer pathway in a copper-containing nitrite reductase by site-directed mutagenesis, spectroscopic, and computational methods

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