A Seemingly Forbidden Octacovalent Structure

Abstract

About a metal atom in the Ta₆Cl₁₂^+a‐like structure, one cannot set up spd hybrid orbitals directed toward all eight neighboring atoms. One can set up spd hybrid orbitals with four orbitals directed toward neighboring halogen atoms and with four orbitals directed towards the middles of neighboring faces of the octahedron. Using such bond orbitals in the over‐all structure and assigning two electrons to each set of overlapping bond orbitals, one gets the value two for a. The degree of overlapping seems favorable.