H3O2 Bridging Ligand in a Metal鈥揙rganic Framework. Insight into the Aqua-Hydroxo鈫擧ydroxyl Equilibrium: A Combined Experimental and Theoretical Study

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• 作者：Richard F. D鈥橵ries ; Victor A. de la Pe帽a-O鈥橲hea ; Natalia Snejko ; Marta Iglesias ; Enrique Guti茅rrez-Puebla ; M. Angeles Monge
• 刊名：The Journal of the American Chemical Society
• 出版年：2013
• 出版时间：April 17, 2013
• 年：2013
• 卷：135
• 期：15
• 页码：5782-5792
• 全文大小：719K
• 年卷期：v.135,no.15(April 17, 2013)
• ISSN：1520-5126

文摘

A metal鈥搊rganic framework (MOF) bearing the aqua-hydroxo species (O₂H₃)^{鈭?/sup> in the framework, as well as the processes that govern the equilibrium aqua-hydroxo (O₂H₃)鈭?/sup>鈫攈ydroxyl (OH) in Sc-MOFs, are studied experimentally and theoretically. Computational studies were employed to determine the relative energies for the two compounds that coexist under certain hydrothermal conditions at pH < 2.8. The thermodynamically more stable [Sc₃(3,5-DSB)₂(渭-O₂H₃)(渭-OH)₂(H₂O)₂] (from now on, (O₂H₃)Sc-MOF; 3,5-DSB = 3,5-disulfobenzoic acid) was obtained as a pure and stable phase. It was impossible to isolate [Sc₃(3,5-DSB)₂(渭-OH)₃(H₂O)₄] as a pure phase, as it turned out to be the precursor of (O₂H₃)Sc-MOF. Additionally, a third compound that appears at pH between 3.5 and 4, [Sc₃(3,5-DSB)(渭-OH)₆(H₂O)] and a fourth, [Sc(3,5-DSB)(Phen)(H₂O)](H₂O), in whose formula neither OH groups nor H₃O₂鈥?/sup> anions appear, are reported for comparative purposes. A study of the (O₂H₃)Sc-MOF electronic structure, and some heterogeneous catalytic tests in cyanosilylation of aldehydes reactions, are also reported.}