期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2018
卷号：115
期号：20
页码：5089-5092
DOI：10.1073/pnas.1801025115
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Molybdenum-dependent nitrogenases catalyze the transformation of dinitrogen into ammonia under ambient conditions. The active site (FeMo cofactor) is the structurally and electronically complex weak-field metal cluster [MoFe7S9C] built of Fe4S3 and MoFe3S3C portions connected by three sulfur bridges and containing an interstitial carbon atom centered in an Fe6 trigonal prism. Chemical synthesis of this cluster is a major challenge in biomimetic inorganic chemistry. One synthetic approach of core ligand metathesis has been developed based on the design and synthesis of unprecedented incomplete ([(Tp*)WFe2S3Q3]−) and complete ([(Tp*)WFe3S3Q4]2−) cubane-type clusters containing bridging halide (Q = halide). These clusters are achieved by template-assisted assembly in the presence of sodium benzophenone ketyl reductant; products are controlled by reaction stoichiometry. Incomplete cubane clusters are subject to a variety of metathesis reactions resulting in substitution of a μ 2-bridging ligand with other bridges such as N3−, MeO−, and EtS−. Reactions of complete cubanes with Me3SiN3 and S8 undergo a redox metathesis process and lead to core ligand displacement and formation of [(Tp*)WFe3S3( μ 3-Q)Cl3]− (Q = Me3SiN2−, S2−). This work affords entry to a wide variety of heteroleptic clusters derivable from incomplete and complete cubanes; examples are provided. Among these is the cluster [(Tp*)WFe3S3( μ 3-NSiMe3)Cl3]−, one of the very few instances of a synthetic Fe–S cluster containing a light atom (C, N, O) in the core, which constitutes a close mimic of the [MoFe3S3C] fragment in FeMo cofactor. Superposition of them and comparison of metric information disclose a clear structural relationship [Tp* = tris(3,5-dimethyl-1-pyrazolyl)hydroborate(1−)].
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