Tuning aromaticity in trigonal alkaline earth metal clusters and their alkali metal salts

✍ Scribed by J. Oscar C. JimÉnez-halla; Eduard Matito; LluÍs Blancafort; Juvencio Robles; Miquel Solà

• Publisher: John Wiley and Sons
• Year: 2009
• Tongue: English
• Weight: 792 KB
• Volume: 30
• Category: Article
• ISSN: 0192-8651
• DOI: 10.1002/jcc.21291

✦ Synopsis

Abstract

In this work, we analyze the geometry and electronic structure of the [X~n~M~3~]^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‐[M~3~]^2−^ unit. The cyclo‐[M~3~]^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‐[M~3~]^2−^ ring and leads to a change from σ‐aromaticity in the bound state of the cyclo‐[M~3~]^2−^ to π‐aromaticity in the XM~3~^−^ and X~2~M~3~ metallic clusters. Our results also show that the aromaticity of the cyclo‐[M~3~]^2−^ unit in the X~2~M~3~ 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 M~3~ ring. The Na~2~Mg~3~, Li~2~Mg~3~, and X~2~Ca~3~ clusters undergo drastic aromaticity alterations when changing the distance from X to the center of the M~3~ ring, whereas X~2~Be~3~ and K~2~Mg~3~ keep its aromaticity relatively constant along this process. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2009