Web Release Date: October 28,
Reactions of AlnIx- with Methyl Iodide: The Enhanced Stability of Al7I and the Chemical Significance of Active Centers
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Contribution from the Departments of Chemistry and Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, and Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284
Received January 18, 2005
Abstract:
AlnIx- are reacted with methyl iodide, and the reaction mechanisms and products are discussed. The relevance of previous studies of the reactions between bare aluminum clusters and methyl iodide is addressed, and the chemical differences reported herein are explained. Particular attention is given to parallels with the known chemistry of alkyl halides on aluminum surfaces, where kinetically mediated etching reactions are prominent. The emergence of Al7I- as the dominant product in the present reactions is addressed via electronic structure calculations, which reveal that the cluster can be described in terms of an electron bound to a "jellium compound". Other significant products of the etching reaction include I-, I3-, and, importantly, the polyhalide-like Al13I2x- clusters. In the Al13Ix- series, clusters with odd values for x are found to be reactive, and those with even x are far more stable. This observation is explained in terms of the presence or absence of active sites.
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