Discrimination of Mononuclear and Dinuclear Dinitrosyl Iron Complexes (DNICs) by S K-Edge X-ray Absorption Spectroscopy: Insight into the Electronic Structure and Reactivity of DNICs

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• 作者：Tsai-Te Lu ; Szu-Hsueh Lai ; Ya-Wen Li ; I-Jui Hsu ; Ling-Yun Jang ; Jyh-Fu Lee ; I-Chia Chen ; Wen-Feng Liaw
• 刊名：Inorganic Chemistry
• 出版年：2011
• 出版时间：June 20, 2011
• 年：2011
• 卷：50
• 期：12
• 页码：5396-5406
• 全文大小：1181K
• 年卷期：v.50,no.12(June 20, 2011)
• ISSN：1520-510X

文摘

In addition to probing the formation of dinitrosyl iron complexes (DNICs) by the characteristic Fe K-edge pre-edge absorption energy ranging from 7113.4 to 7113.8 eV, the distinct S K-edge pre-edge absorption energy and pattern can serve as an efficient tool to unambiguously characterize and discriminate mononuclear DNICs and dinuclear DNICs containing bridged-thiolate and bridged-sulfide ligands. The higher Fe鈥揝 bond covalency modulated by the stronger electron-donating thiolates promotes the Fe 鈫?NO 蟺-electron back-donation to strengthen the Fe鈥揘O bond and weaken the NO-release ability of the mononuclear DNICs, which is supported by the Raman 谓(Fe鈥揘O) stretching frequency. The Fe鈥揝 bond covalency of DNICs further rationalizes the binding preference of the {Fe(NO)₂} motif toward thiolates following the trend of [SEt]^{鈭?/sup> > [SPh]鈭?/sup> > [SC₇H₄SN]鈭?/sup>. The relative d-manifold energy derived from S K-edge XAS as well as the Fe K-edge pre-edge energy reveals that the electronic structure of the {Fe(NO)₂}9 core of the mononuclear DNICs [(NO)₂Fe(SR)₂]鈭?/sup> is best described as {FeIII(NO鈥?/sup>)₂}9 compared to [{FeIII(NO鈥?/sup>)₂}9鈥搟FeIII(NO鈥?/sup>)₂}9] for the dinuclear DNICs [Fe₂(渭-SEt)(渭-S)(NO)₄]鈭?/sup> and [Fe₂(渭-S)₂(NO)₄]2鈥?/sup>.}