Photoelectron Spectroscopy and Electronic Structure Calculations of d1 Vanadocene Compounds with Chelated Dithiolate Ligands: Implications for Pyranopterin Mo/W Enzymes

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• 作者：Matthew A. Cranswick ; Alice Dawson ; J. Jon A. Cooney ; Nadine E. Gruhn ; Dennis L. Lichtenberger ; John H. Enemark
• 刊名：Inorganic Chemistry
• 出版年：2007
• 出版时间：December 10, 2007
• 年：2007
• 卷：46
• 期：25
• 页码：10639 - 10646
• 全文大小：192K
• 年卷期：v.46,no.25(December 10, 2007)
• ISSN：1520-510X

文摘

Gas-phase photoelectron spectroscopy and density functional theory have been used to investigate the electronicstructures of open-shell bent vanadocene compounds with chelating dithiolate ligands, which are minimum molecularmodels of the active sites of pyranopterin Mo/W enzymes. The compounds Cp₂V(dithiolate) [where dithiolate is1,2-ethenedithiolate (S₂C₂H₂) or 1,2-benzenedithiolate (bdt), and Cp is cyclopentadienyl] provide access to a 17-electron, d¹ electron configuration at the metal center. Comparison with previously studied Cp₂M(dithiolate) complexes,where M is Ti and Mo (respectively d⁰ and d² electron configurations), allows evaluation of d⁰, d¹, and d² electronicconfigurations of the metal center that are analogues for the metal oxidation states present throughout the catalyticcycle of these enzymes. A "dithiolate-folding effect" that involves an interaction between the vanadium d orbitalsand sulfur p orbitals is shown to stabilize the d¹ metal center, allowing the d¹ electron configuration and geometryto act as a low-energy electron pathway intermediate between the d⁰ and d² electron configurations of the enzyme.