Light-Atom Influences on the Electronic Structures of Iron鈥揝ulfur Clusters

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• 作者：Christopher J. Pollock ; Lay Ling Tan ; Wei Zhang ; Kyle M. Lancaster ; Sonny C. Lee ; Serena DeBeer
• 刊名：Inorganic Chemistry
• 出版年：2014
• 出版时间：March 3, 2014
• 年：2014
• 卷：53
• 期：5
• 页码：2591-2597
• 全文大小：375K
• 年卷期：v.53,no.5(March 3, 2014)
• ISSN：1520-510X

文摘

Ligand K-edge X-ray absorption spectroscopy was used to study dimeric and tetrameric Cl-terminated Fe鈥揝 clusters with variable numbers of S^{2鈥?/sup> substituted by NtBu2鈥?/sup> (NtBu2鈥?/sup> = tertbutylimido) ligands to gain insights into the functional role of the interstitial light atom in the iron鈥搈olybdenum cofactor (FeMoco) of nitrogenase. These studies are complemented by time-dependent density functional theory analysis to quantify the relative effects on Fe鈥揝 and Fe鈥揅l bonding. The results show that NtBu2鈥?/sup> substitution dramatically affects the electronic structure of dimeric clusters, while the impact on tetrameric clusters is small. Strong agreement between experiment and theory merited extension of this analysis to hypothetical clusters with S2鈥?/sup> substituted by N and C-atom donor ligands as well as FeMoco itself. These results show that very strong electron donors are required to appreciably modulate the electronic structure of tetrameric (or larger) iron sulfur clusters, pointing to a possible role of the central C4鈥?/sup> in FeMoco.}