Structure and stability of small titanium/oxygen clusters studied by ab initio quantum chemical calculations

Ab initio calcns. have been performed on TinO2n-δ clusters, with n = 1-3 and δ = 0, 1, as well as on some of their ionized species. The geometries of the different clusters were optimized and vibrational analyses were performed at the ground-state equil. geometries. The Ti-O bond lengths are essentially detd. by the coordination nos. of the resp. atoms, independent of n. The clusters are characterized by having any low pendant oxygen vibrational frequencies. The ionization energies for the (TiO2)n clusters were significantly higher than those of oxygen-deficient, TinO2n-1, clusters. Some anomalous features of the n = 1 cluster, TiO2, as compared to clusters with n > 1, are discussed. Recent exptl. mass spectrometric observations on titanium oxide clusters are discussed in the light of the present findings.