Titanium(II) oxide (TiO) is an inorganicchemical compound of titanium and oxygen. It can be prepared from titanium dioxide and titanium metal at 1500 °C. It is non-stoichiometric in a range TiO0.7 to TiO1.3 and this is caused by vacancies of either Ti or O in the defect rock salt structure. In pure TiO 15% of both Ti and O sites are vacant. Careful annealing can cause ordering of the vacancies producing a monoclinic form which has 5 TiO units in the primitive cell that exhibits lower resistivity. A high temperature form with titanium atoms with trigonal prismatic coordination is also known. Acid solutions of TiO are stable for a short time then decompose to give hydrogen:
2Ti2+(aq) + 2H+(aq) → 2Ti3+(aq) + H2(g)
Gas-phase TiO shows strong bands in the optical spectra of cool (M-type) stars. In 2017, TiO was detected in an exoplanet atmosphere for the first time. Additionally, evidence has been obtained for the presence of the diatomic molecule TiO in the interstellar medium.
^ abcdHolleman, Arnold Frederik; Wiberg, Egon (2001), Wiberg, Nils (ed.), Inorganic Chemistry, translated by Eagleson, Mary; Brewer, William, San Diego/Berlin: Academic Press/De Gruyter, ISBN0-12-352651-5
^Electrical and Magnetic Properties of TiO and VO, Banus M. D., Reed T. B., Strauss A. J., Phys. Rev. B 5, 2775 - 2784, (1972)doi:10.1103/PhysRevB.5.2775