Insight into One-Electron Oxidation of the {Fe(NO)2}9 Dinitrosyl Iron Complex (DNIC): Aminyl Radical Stabilized by [Fe(NO)2] Motif

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• 作者：Chih-Chin Tsou ; Fu-Te Tsai ; Huang-Yeh Chen ; I-Jui Hsu ; Wen-Feng Liaw
• 刊名：Inorganic Chemistry
• 出版年：2013
• 出版时间：February 4, 2013
• 年：2013
• 卷：52
• 期：3
• 页码：1631-1639
• 全文大小：497K
• 年卷期：v.52,no.3(February 4, 2013)
• ISSN：1520-510X

文摘

A reversible redox reaction ({Fe(NO)₂}⁹ DNIC [(NO)₂Fe(N(Mes)(TMS))₂]^{鈭?/sup> (4) oxidized-form DNIC [(NO)₂Fe(N(Mes)(TMS))₂] (5) (Mes = mesityl, TMS = trimethylsilane)), characterized by IR, UV鈥搗is, 1H/15N NMR, SQUID, XAS, single-crystal X-ray structure, and DFT calculation, was demonstrated. The electronic structure of the oxidized-form DNIC 5 (S_total = 0) may be best described as the delocalized aminyl radical [(N(Mes)(TMS))₂]₂鈥撯€?/sup> stabilized by the electron-deficient {FeIII(NO鈥?/sup>)₂}9 motif, that is, substantial spin is delocalized onto the [(N(Mes)(TMS))₂]₂鈥撯€?/sup> such that the highly covalent dinitrosyl iron core (DNIC) is preserved. In addition to IR, EPR (g 鈮?2.03 for {Fe(NO)₂}9), single-crystal X-ray structure (Fe鈥揘(O) and N鈥揙 bond distances), and Fe K-edge pre-edge energy (7113.1鈥?113.3 eV for {Fe(NO)₂}10 vs 7113.4鈥?113.9 eV for {Fe(NO)₂}9), the 15N NMR spectrum of [Fe(15NO)₂] was also explored to serve as an efficient tool to characterize and discriminate {Fe(NO)₂}9 (未 23.1鈥?6.1 ppm) and {Fe(NO)₂}10 (未 鈭?.8鈥?5.0 ppm) DNICs. To the best of our knowledge, DNIC 5 is the first structurally characterized tetrahedral DNIC formulated as covalent鈥揹elocalized [{FeIII(NO鈥?/sup>)₂}9鈥揫N(Mes)(TMS)]₂鈥撯€?/sup>]. This result may explain why all tetrahedral DNICs containing monodentate-coordinate ligands isolated and characterized nowadays are confined in the {Fe(NO)₂}9 and {Fe(NO)₂}10 DNICs in chemistry and biology.}