Square Planar to Rectangular Distortion in Transition-Metal Compounds of Edge-Sharing Square Planar UnitsMX4

Abstract In transition metal compounds of edge-sharing square planar MX 4 units ( M =group 10, group 11; X =O, S, Se), a square planar to rectangular distortion is observed. The causes for this distortion in MX 2 ladder chains, M 3 X 4 honeycomb layers, and 3D MX lattices were examined by performing extended Huckel tight binding electronic band structure calculations. The primary cause for the distortion is the reduction of the four-electron two-orbital destabilizing interactions among the p -orbitals of X .