Photochemical Dihydrogen Production Using an Analogue of the Active Site of [NiFe] Hydrogenase

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• 作者：Peter A. Summers ; Joe Dawson ; Fabio Ghiotto ; Magnus W. D. Hanson-Heine ; Khuong Q. Vuong ; E. Stephen Davies ; Xue-Z. Sun ; Nicholas A. Besley ; Jonathan McMaster ; Michael W. George ; Martin Schr枚der
• 刊名：Inorganic Chemistry
• 出版年：2014
• 出版时间：May 5, 2014
• 年：2014
• 卷：53
• 期：9
• 页码：4430-4439
• 全文大小：465K
• 年卷期：v.53,no.9(May 5, 2014)
• ISSN：1520-510X

文摘

Photoproduction of dihydrogen (H₂) by a low molecular weight analogue of the active site of [NiFe] hydrogenase has been investigated by reduction of the [NiFe₂] cluster, 1, by a photosensitier PS (PS = [ReCl(CO)₃(bpy)] or [Ru(bpy)₃][PF₆]₂). Reductive quenching of the ³MLCT excited state of the photosensitizer by NEt₃ or N(CH₂CH₂OH)₃ (TEOA) generates PS^{鈥⑩€?/b>}, and subsequent intermolecular electron transfer to 1 produces the reduced anionic form of 1. Time-resolved infrared spectroscopy (TRIR) has been used to probe the intermediates throughout the reduction of 1 and subsequent photocatalytic H₂ production from [HTEOA][BF₄], which was monitored by gas chromatography. Two structural isomers of the reduced form of 1 (1a^{鈥⑩€?/b>} and 1b^{鈥⑩€?/b>}) were detected by Fourier transform infrared spectroscopy (FTIR) in both CH₃CN and DMF (dimethylformamide), while only 1a^{鈥⑩€?/b>} was detected in CH₂Cl₂. Structures for these intermediates are proposed from the results of density functional theory calculations and FTIR spectroscopy. 1a^{鈥⑩€?/b>} is assigned to a similar structure to 1 with six terminal carbonyl ligands, while calculations suggest that in 1b^{鈥⑩€?/b>} two of the carbonyl groups bridge the Fe centers, consistent with the peak observed at 1714 cm^鈥? in the FTIR spectrum for 1b^{鈥⑩€?/b>} in CH₃CN, assigned to a 谓(CO) stretching vibration. Formation of 1a^{鈥⑩€?/b>} and 1b^{鈥⑩€?/b>} and production of H₂ was studied in CH₃CN, DMF, and CH₂Cl₂. Although the more catalytically active species (1a^{鈥⑩€?/b>} or 1b^{鈥⑩€?/b>}) could not be determined, photocatalysis was observed only in CH₃CN and DMF.