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Abstract: Herein we report the systematic exploration of the potential energy surfaces of a series of clusters with formula E5M7+ (E=C‐Pb and M=Li‐Cs). Fifteen of these combinations adopt a D5h three‐dimensional seven‐pointed star‐like structure in a singlet state, where M atoms interact electrostatically with the E5 ring. The determining factors in the relative preference of having the D5h structure over the most competitive isomer or vice‐versa are analyzed. These star‐shaped systems satisfy the 4n+2 Hückel's rule and exhibit a strong diatropic (σ and π) response to an external magnetic field. [ABSTRACT FROM AUTHOR]

Abstract: The structure, bonding, and stability of clusters with the empirical formula CE5− (E=Al–Tl) have been analyzed by means of high‐level computations. The results indicate that, whereas aluminum and gallium clusters have C2v structures with a planar tetracoordinate carbon (ptC), their heavier homologues prefer three‐dimensional C4v forms with a pentacoordinate carbon center over the ptC one. The reason for such a preference is a delicate balance between the interaction energy of the fifth E atom with CE4 and the distortion energy. Moreover, bonding analysis shows that the ptC systems can be better described as CE4−, with 17‐valence electrons interacting with E. The ptC core in these systems exhibits double aromatic (both σ and π) behavior, but the σ contribution is dominating. [ABSTRACT FROM AUTHOR]