The Structure of ([W3Q4X3(dmpe)3]+, Y-) Ion Pairs (Q = S, Se; X = H, OH, Br; Y = BF4, PF6, dmpe = Me2

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• 作者：André ; s G. Algarra ; Manuel G. Basallote ; M. Jesú ; s Fern&aacute ; ndez-Trujillo ; Rosa Llusar ; Vicent S. Safont ; and Cristian Vicent
• 刊名：Inorganic Chemistry
• 出版年：2006
• 出版时间：July 24, 2006
• 年：2006
• 卷：45
• 期：15
• 页码：5774 - 5784
• 全文大小：286K
• 年卷期：v.45,no.15(July 24, 2006)
• ISSN：1520-510X

文摘

The <SUP>1H,¹⁹F HOESY spectra of the title compounds in CD₂Cl₂ solution indicate that the cluster cations form ion pairswith the BF₄^- and PF₆^- anions with a well-defined interionic structure that appears to be basically determinedessentially by the nature of the X^- ligand. For the clusters with X = H and OH, the structure of the ion pairs issuch that the counteranion (Y^-) and the X^- ligands are placed close to each other. However, when the size andelectron density of X^- increase (X = Br), Y^- is forced to move to a different site, far away from X^-. The relevanceof ion-pairing on the chemistry of these compounds is clearly seen through a decrease in the rate of protontransfer from HCl to the hydride cluster [W₃S₄H₃(dmpe)₃]⁺ in the presence of an excess of BF₄^-. The kinetic datafor this reaction can be rationalized by considering that the ([W₃S₄H₃(dmpe)₃]⁺, BF₄^-) ion pairs are unproductivein the proton-transfer process. Theoretical calculations indicate that the real behavior can be more complex. Althoughthe cluster can still form adducts with HCl in the presence of BF₄^-, the structures of the most-stable BF₄^--containingHCl adducts show H···H distances too large to allow the subsequent release of H₂. In addition, the effectiveconcentration of HCl is also reduced because of the formation of adducts as ClH···BF₄^-. As a consequence ofboth effects, the proton transfer takes place more slowly than for the case of the dihydrogen-bonded HCl adductresulting from the unpaired cluster.