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Subject : « ‘[FeFe] Hydrogenase Subunit Mimics containing Selenium' »
Abstract :
In order to study the influence of sulfur and selenium atoms incorporated into the structure of complexes that model the active site of [FeFe] hydrogenases, a series of diiron dithiolato and diselenolato complexes of the form [Fe2(CO)6{μ-(XCH2)2E}] (X = Se, Te; E = CH2, CHMe or CMe2, S, Se) have been prepared and characterized.[1] [FeFe] hydrogenase subunit mimics containing larger chalcogens such as Se or Te have exhibited greater electron richness at the metal centers. However, chalcogen substitution from S to Se or Te also causes an increase in the Fe–Fe bond length, which disfavours the formation of a carbonyl-bridged “rotated” structure. The replacement of S atoms of diiron dithiolato model complexes by more electropositive Se atoms leads to an enhancement of the catalytic activity of some [FeFe] hydrogenase models. This could be attributed to an increase of the electron density at the Fe atoms and faster electron transfer in complexes containing [2Fe2Se] rather than [2Fe2S] cores. As a consequence, we have found that the replacement of the μ-S atoms in the dithiolato linker by Se atoms enhances the electron density of the iron cores, which makes it more susceptible to be protonated across the Fe–Fe vector by using a strong acid such as HBF4·Et2O. Moreover, the replacement of the bridgehead carbon atom by the Sn atom in combination with the μ-Se moieties makes it possible for these complexes to be partially protonated employing a moderate acid such as CF3CO2H.[2,3]
References:
[1] R. Trautwein, L. R. Almazahreh, H. Görls, W. Weigand, Dalton Trans. 2015, 44, 18780. [2] H. Abul-Futouh, L. R. Almazahreh, T. Sakamoto, N. Y. T. Stessman, D. L. Lichtenberger, R. S. Glass,H. Görls, M. El-khateeb, P. Schollhammer, G. Mloston and
W. Weigand, Chem. – Eur. J., 2017, 23, 346. [3] H. Abul-Futouh, M. El-khateeb, H. Görls, K. Jamil Asali, W. Weigand, Dalton Trans., 2017, 46, 2937.[:]