Tuning aromaticity in trigonal alkaline earth metal clusters and their alkali metal salts |
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| Authors: | J Oscar C JimÉnez‐halla Eduard Matito LluÍs Blancafort Juvencio Robles Miquel Solà |
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| Institution: | 1. Institut de Química Computacional and Departament de Química, Universitat de Girona, Campus de Montilivi, 17071 Girona, Catalonia, Spain;2. Department of Chemistry, The Lundbeck Foundation Center for Theoretical Chemistry, University of Aarhus, Langelandsgade 140, DK‐8000 Aarhus C, Denmark;3. Departamento de Farmacia, División de Ciencias Naturales y Exactas, Universidad de Guanajuato, Noria Alta s/n 36050 Guanajuato, Gto. Mexico |
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| Abstract: | In this work, we analyze the geometry and electronic structure of the XnM3]n?2 species (M = Be, Mg, and Ca; X = Li, Na, and K; n = 0, 1, and 2), with special emphasis on the electron delocalization properties and aromaticity of the cyclo‐M3]2? unit. The cyclo‐M3]2? ring is held together through a three‐center two‐electron bond of σ‐character. Interestingly, the interaction of these small clusters with alkali metals stabilizes the cyclo‐M3]2? ring and leads to a change from σ‐aromaticity in the bound state of the cyclo‐M3]2? to π‐aromaticity in the XM3? and X2M3 metallic clusters. Our results also show that the aromaticity of the cyclo‐M3]2? unit in the X2M3 metallic clusters depends on the nature of X and M. Moreover, we explored the possibility for tuning the aromaticity by simply moving X perpendicularly to the center of the M3 ring. The Na2Mg3, Li2Mg3, and X2Ca3 clusters undergo drastic aromaticity alterations when changing the distance from X to the center of the M3 ring, whereas X2Be3 and K2Mg3 keep its aromaticity relatively constant along this process. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2009 |
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| Keywords: | 3c‐2e bonding alkaline earth metal clusters σ ‐aromaticity π ‐aromaticity aromaticity tuning DFT calculations |
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