X‐Ray Emission Spectroscopy: A Spectroscopic Measure for the Determination of NO Oxidation States in Fe–NO Complexes |
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| Authors: | Prof Tsai‐Te Lu Dr Tsu‐Chien Weng Prof Wen‐Feng Liaw |
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| Affiliation: | 1. Department of Chemistry, Chung Yuan Christian University, No. 200, Chung Pei Rd. Chungli, 32023 (Taiwan);2. SLAC National Accelerator Laboratory, 2575 Sand Hill Rd. Menlo Park, CA 94025 (USA);3. Department of Chemistry, National Tsing Hua University, No. 101, Section 2, Kuang‐Fu Rd. Hsinchu, 30013 (Taiwan) |
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| Abstract: | Extensive study of the electronic structure of Fe‐NO complexes using a variety of spectroscopic methods was attempted to understand how iron controls the binding and release of nitric oxide. The comparable energy levels of NO π* orbitals and Fe 3d orbitals complicate the bonding interaction within Fe? NO complexes and puzzle the quantitative assignment of NO oxidation state. Enemark–Feltham notation, {Fe(NO)x}n, was devised to circumvent this puzzle. This 40‐year puzzle is revisited using valence‐to‐core X‐ray emission spectroscopy (V2C XES) in combination with computational study. DFT calculation establishes a linear relationship between ΔEσ2s*‐σ2p of NO and its oxidation state. V2C Fe XES study of Fe? NO complexes reveals the ΔEσ2s*‐σ2p of NO derived from NO σ2s*/σ2p→Fe1s transitions and determines NO oxidation state in Fe? NO complexes. Quantitative assignment of NO oxidation state will correlate the feasible redox process of nitric oxide and Fe‐nitrosylation biology. |
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| Keywords: | bioinorganic chemistry iron nitrosyl complexes X‐ray emission spectroscopy |
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