Titanium(II) oxide (TiO) is an inorganic chemical compound of titanium and oxygen. It can be prepared from titanium dioxide and titanium metal at 1500 °C.[1] 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.[1] In pure TiO 15% of both Ti and O sites are vacant,[1] as the vacancies allow metal-metal bonding between adjacent Ti centres. 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.[2] A high temperature form with titanium atoms with trigonal prismatic coordination is also known.[3] Acid solutions of TiO are stable for a short time then decompose to give hydrogen:[1]
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| Names | |
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| IUPAC name
Titanium(II) oxide | |
| Other names
Titanium monoxide | |
| Identifiers | |
3D model (JSmol) |
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| ECHA InfoCard | 100.032.020 
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PubChem CID |
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CompTox Dashboard (EPA) |
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| Properties | |
| TiO | |
| Molar mass | 63.866 g/mol |
| Appearance | bronze crystals |
| Density | 4.95 g/cm3 |
| Melting point | 1,750 °C (3,180 °F; 2,020 K) |
| Structure | |
| cubic | |
| Hazards | |
| Flash point | Non-flammable |
| Related compounds | |
| Titanium(III) oxide Titanium(III,IV) oxide Titanium(IV) oxide | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
Gas-phase TiO shows strong bands in the optical spectra of cool (M-type) stars.[4][5] In 2017, TiO was claimed to be detected in an exoplanet atmosphere for the first time; a result which is still debated in the literature.[6][7] Additionally, evidence has been obtained for the presence of the diatomic molecule TiO in the interstellar medium.[8]
