Abstract: | The molecular and electronic structures of some polyhedral alternate molecules XnYn, where n=12, 16; X=B, Al, Si; Y=N,P,C, and of homoatomic clusters C24, Si24, C32, and Si32 are calculated in a valence approximation by the MNDO method. It is suggested that the σ-frameworks of these molecules are
formed of four- and six-membered rings, with each X atom having only Y atoms as neighbors. The singlet states of all these
systems have local minima on the corresponding potential energy surfaces with Th symmetry for n=12 and Td symmetry for n=16. The main structural parameters, heats of formation, ionization potentials, and effective charge distributions
are given. It is concluded that the XnYn heteroatomic clusters can exist when X and Y are atoms of Group III and V elements, respectively, or both are atoms of Group
IV elements.
A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences. Translated fromZhurnal Strukturnoi Khimii, Vol. 36, No. 6, pp.976–982, November–December, 1995.
Translated by L. Smolina |