The electron-density distribution in Ti2O3 at room temperature has been determined from single-crystal X-ray diffraction data. The deformation maps show maxima of 0.15 e Å-3 between the Ti atoms sharing a common face of O-atom octahedra, and maxima of 0.18 e Å-3 between the O atoms and their four nearest Ti neighbours. These observations support the general view concerning the bonding in Ti2O3 and correlate well with the results of theoretical band-structure calculations. In particular, they confirm the existence of a metal-metal bond which is directed parallel to the ternary axis and is responsible for the anomalously low c/a ratio of this compound.
Vincent, M. G., Yvon, K., Grüttner, A. and Ashkenazi, J. (1980), Electron-density studies of metal–metal bonds. I. The deformation density of Ti2 O3 at 295 K. Acta Crystallographica Section A, 36: 803–808. doi: 10.1107/S0567739480001611