Physical Sciences and Mathematics Commons^™

A Theoretical Study Of Models For X2y2 Zintl Ions, Robert J. Cave, Ernest R. Davidson, Philippe Sautet, Enric Canadell, Odile Eisenstein

All HMC Faculty Publications and Research

Ab initio and extended Hückel calculations have been used to discuss the bonding scheme in X₂Y₂ neutral and ionic main group clusters. A qualitative analysis suggests that two different electron counts, 20 and 22, are possible for the butterfly structures of these systems. This results from two orbital crossings in the correlation diagram for the tetrahedral (T_d) -> butterfly (C_2v) -> square-planar (D_2h) transformation. Detailed ab initio computations substantiate this analysis and show that the 20-electron butterfly structure becomes increasingly favored over the tetrahedral one in X₂Y₂ clusters when the 2 atoms have increasing electronegativity difference. …