High level ab initio and density functional study of TeF₆⁺ and TeCl₆⁺: Attainability of +7 oxidation state for tellurium.

This article focuses on the theoretical investigation of the possibility that tellurium (Te), an sp-block element, can attain a rare +7 oxidation state through the formation of TeCl6+ with a distorted octahedron (DOH) structure. Using high-level ab initio coupled-cluster calculations, the study finds that while TeF6+ favors a structure with one elongated axial bond (aEOH), TeCl6+ adopts a more stable DOH structure where all six chlorine atoms are covalently bonded to Te, supporting the +7 oxidation state. The research also identifies a novel isomerization mechanism termed associated pseudorotation (APR) between the aEOH and DOH forms of TeF6+. Thermal stability analyses suggest that the DOH structure of TeCl6+ is stable at room temperature, and the authors propose experimental detection methods to confirm these findings, which could expand the known chemistry of tellurium.