Stability of charges in titanium compounds and charge transfer to oxygen in titanium dioxide

TL;DR

This study analyzes charge distribution in titanium compounds, revealing that formal oxidation states often fail to describe redox behavior, with titanium charges remaining notably stable across various environments.

Contribution

It provides detailed charge density analysis in titanium compounds, highlighting limitations of formal oxidation states in describing redox processes.

Findings

Titanium charges remain stable and do not fall below one electron.

Formal oxidation states often do not reflect actual charge distributions.

Charge transfer to oxygen is consistent with partial ionic character.

Abstract

We investigate the charge density distribution in titanium dioxide, molecular titanium complexes and a variety of periodic titanium compounds using delocalization indices and Bader charge analysis. Our results are in agreement with previous experimental and theoretical investigations on the charge stability and deviation from formal oxidation states in transition metal compounds. We present examples for practically relevant redox processes, using molecular titanium dioxide model systems, that illustrate the failure of formal oxidation states to account for some redox phenomena. We observe a pronounced charge stability on titanium for trial systems which are expected to be mainly ionic. No environment tested by us is capable to reduce the local titanium charge remainder below one electron.