用 X 射线发射光谱法对 Ni-N-O 键角和 NO 活化进行定量分析。
Quantification of Ni-N-O Bond Angles and NO Activation by X-ray Emission Spectroscopy.
机构信息
Department of Chemistry & Biochemistry, California State Polytechnic University, Pomona, California 91768, United States.
Department of Chemistry, Georgetown University, Box 571227, Washington, D.C. 20057, United States.
出版信息
Inorg Chem. 2021 Jan 18;60(2):736-744. doi: 10.1021/acs.inorgchem.0c02724. Epub 2020 Dec 29.
A series of β-diketiminate Ni-NO complexes with a range of NO binding modes and oxidation states were studied by X-ray emission spectroscopy (XES). The results demonstrate that XES can directly probe and distinguish end-on vs side-on NO coordination modes as well as one-electron NO reduction. Density functional theory (DFT) calculations show that the transition from the NO 2s2s σ* orbital has higher intensity for end-on NO coordination than for side-on NO coordination, whereas the 2s2s σ orbital has lower intensity. XES calculations in which the Ni-N-O bond angle was fixed over the range from 80° to 176° suggest that differences in NO coordination angles of ∼10° could be experimentally distinguished. Calculations of Cu nitrite reductase (NiR) demonstrate the utility of XES for characterizing NO intermediates in metalloenzymes. This work shows the capability of XES to distinguish NO coordination modes and oxidation states at Ni and highlights applications in quantifying small molecule activation in enzymes.
采用 X 射线发射光谱（XES）研究了一系列具有不同 NO 结合模式和氧化态的β-二酮腙 Ni-NO 配合物。结果表明，XES 可直接探测和区分端到端与侧到侧的 NO 配位模式以及单电子 NO 还原。密度泛函理论（DFT）计算表明，对于端到端 NO 配位，NO 2s2s σ*轨道的跃迁强度高于侧到侧 NO 配位，而 2s2s σ 轨道的跃迁强度较低。在 Ni-N-O 键角固定在 80°至 176°范围内的 XES 计算表明，实验上可以区分大约 10°的 NO 配位角差异。铜亚硝酸盐还原酶（NiR）的计算表明 XES 可用于表征金属酶中的 NO 中间体。这项工作展示了 XES 区分 Ni 上的 NO 配位模式和氧化态的能力，并强调了其在定量酶中小分子活化方面的应用。
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