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Various isomers of the trigonal dianion metal clusters, X32-, X = Be, Mg, Ca, and their mono- and disodium complexes are optimized at the B3LYP/6-311+G(d) level. Different conceptual density functional theory based reactivity descriptors as well as the induced magnetic field values are calculated to understand the stability and aromaticity of these systems. Possibility of bond stretch isomerism is explored. Genetic algorithm results lend additional insights into the structures of these isomers. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2010 [ABSTRACT FROM AUTHOR]

Theoretical evidence for the first neutral and anionic global-minimum structures possessing a planar pentacoordinate carbon is reported. [ABSTRACT FROM AUTHOR]

We have explored in detail the potential energy surfaces of the Si5Lin5-6 (n = 5-7) systems. We found that it is feasible to design three-dimensional star-like silicon structures using the appropriate ligands. The global minimum structure for Si5Li7+ has a perfect seven-peak star-like structure. The title compounds comprise, essentially, the Si56- ring interacting with lithium cations. The ionic character of the Si-Li interactions induces the formation of a bridged structure. Concomitantly, our calculations show that the reduction of the Pauli repulsion and the maximization of the orbital contribution are also significant for the star-like structure formation. Additionally, the MO analysis of the systems suggests that the role of the lithium atoms is to provide the precise number of electrons to the central Si5 unit. This is confirmed by the magnetic properties, which show that electron delocalization enhances the stability of the star-like structures proposed here. [ABSTRACT FROM AUTHOR]