Rhenium Bronze Oxide Containing Tellurium Ions with Two Lone Pairs

Hexagonal bronze oxides are represented by the chemical formula A_<i>x</i>MO₃, where A is an electropositive element such as alkali metal or alkaline earth metal and M is a transition metal such as Mo, W, or Re. We report the first synthesis of a tellurium-containing rhenium bronze oxide, Te_0.30ReO₃. The compound has an orthorhombic crystal structure, with tellurium located within the <i>ab</i> plane along with rhenium and oxygen, and planarly coordinated to three oxygen atoms. Electron localization function (ELF) analysis revealed that tellurium has two ELF attractors above and below the TeO₃ plane and that the ELF structure around tellurium is similar to that of ClF₃. Based on valence shell electron pair repulsion theory, two equatorial positions in the coordination structure of the trigonal bipyramid are occupied by lone pairs and the remaining three positions are occupied by oxygen. Electron density calculations demonstrated that the unique coordination structure of the tellurium arises from the hybridization of the 5s and 5p orbitals of tellurium with the 2p orbitals of oxygen.