Tuning aromaticity in trigonal alkaline earth metal clusters and their alkali metal salts.
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 sigma-character. Interestingly, the interaction of these small clusters with alkali metals stabilizes the cyclo-[M(3)](2-) ring and leads to a change from sigma-aromaticity in the bound state of the cyclo-[M(3)](2-) to pi-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.
Jiménez-Halla
J Oscar C
JO
Institut de Química Computacional and Departament de Química, Universitat de Girona, Campus de Montilivi, 17071 Girona, Catalonia, Spain.
Matito
Eduard
E
Blancafort
Lluís
L
Robles
Juvencio
J
Solà
Miquel
M
D008672:Metals, Alkali / Q000737:chemistry*; D008673:Metals, Alkaline Earth / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D011789:Quantum Theory; D012492:Salts / Q000737:chemistry*
D008672:Metals, Alkali; D008673:Metals, Alkaline Earth; D012492:Salts