Stable Positions of a Metal Ion Relative to an Icosahedral Borane

Abstract

ABSTRACTWe have considered a series of conformations of the neutral complex [Mg+B12H12] including those in which the Mg is internal to the icosahedral B12 cage. Self-consistent molecular-orbital calculations to determine the total cluster energy have been carried out as the Mg atom is moved from the center of the borane to a position 10Å from the center (outside the borane cage). Two energy minima are found as a function of position. One is outside the borane cage. at 3.0–3.5Å from the center; the second is at the center of the borane cage. The central minimum is the deeper of the two if Mg 3d orbitals are included in the basis set.Many atoms have a low ionization energy and are, as ions, of appropriate “size” to fit inside a B12 cage. Incorporation of such ions into B12 cages in solids may offer significant flexibility in the development of refractory semiconductors and thermoelectrics.