A Dirac molecular orbital study for the tetragonal compression in the RuY6I122- cluster

Symmetry-adapted angular momentum basis functions have been generated for the O-h* and D-4h* molecular double point groups. These basis functions are used to obtain the relativistic cluster orbitals for the octahedral (O-h) and the compressed octahedral geometries (D-4h) of the RuY6I122- cluster. The Jahn-Teller effect removes the octahedral Gamma(8)(-) orbital degeneracy, thus giving rise to a stable tetragonal cluster with a singlet Gamma(7)(-) ground state. The interstitial Ru atom acquires more electrons in the tetragonally compressed cluster structure than in its octahedral arrangement.