Molybdenum Oxides versus Molybdenum Sulfides: Geometric and Electronic Structures of Mo3Xy鈭?/sup> (X = O, S and y = 6, 9) Clusters

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• 作者：Nicholas J. Mayhall ; Edwin L. Becher III ; Arefin Chowdhury ; Krishnan Raghavachari
• 刊名：Journal of Physical Chemistry A
• 出版年：2011
• 出版时间：March 24, 2011
• 年：2011
• 卷：115
• 期：11
• 页码：2291-2296
• 全文大小：894K
• 年卷期：v.115,no.11(March 24, 2011)
• ISSN：1520-5215

文摘

We have conducted a comparative computational investigation of the molecular structure and water adsorption properties of molybdenum oxide and sulfide clusters using density functional theory methods. We have found that while Mo₃O₆^{鈭?/sup> and Mo₃S₆鈭?/sup> assume very similar ring-type isomers, Mo₃O₉鈭?/sup> and Mo₃S₉鈭?/sup> clusters are very different with Mo₃O₉鈭?/sup> having a ring-type structure and Mo₃S₉鈭?/sup> having a more open, linear-type geometry. The more rigid (Mo鈭扴鈭扢o) bond angle is the primary geometric property responsible for producing such different lowest energy isomers. By computing molecular complexation energies, it is observed that water is found to adsorb more strongly to Mo₃O₆鈭?/sup> than to Mo₃S₆鈭?/sup>, due to a stronger oxide鈭抴ater hydrogen bond, although dispersion effects reduce this difference when molybdenum centers contribute to the binding. Investigating the energetics of dissociative water addition to Mo₃X₆鈭?/sup> clusters, we find that, while the oxide cluster shows kinetic site-selectivity (bridging position vs terminal position), the sulfide cluster exhibits thermodynamic site-selectivity.}