Результаты исследований: Научные публикации в периодических изданиях › статья › Рецензирование
Gas phase oligomer formation during TiCl4 ammonolysis is theoretically investigated at the DFT B3LYP level of theory with double-ζ quality basis set. Several possible isomers of the dimeric [TiClxNHx-1(NH3)n]2 species (x=3, 2; n=0, 1) have been considered. Dimerization of amido compounds is exothermic by about 10 kcalmol-1, but disfavored by entropy. The latter factor prevents the existence of the amido dimers in the gas phase thermodynamic equilibrium. The dimerization processes of imido compounds are much more exothermic (by about 94 kcalmol-1). A cubic [ClTiN]4 cluster is predicted to be a viable molecular form in the gas phase above 1400 °C. Reduction of Ti(IV) to Ti(III) via hydrazine formation from the [TiCl3NH2(NH3)]2 dimers is less endothermic (∼40 kcalmol-1) than Ti-Cl bond rupture (∼82.5 kcalmol-1). The overall endothermicity of the formation of N2H4 bridged Ti(III) dimer [Cl2(H3N)Ti(μ-Cl)2(μ-N2H4 )Ti(NH3)Cl2] from TiCl4 and NH3 is only 6.6 kcalmol-1. Additional coordination of two ammonia molecules to the [Cl3TiNH2]2 dimer facilitates the elimination of Cl atom.
Язык оригинала | английский |
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Страницы (с-по) | 109-116 |
Число страниц | 8 |
Журнал | Computational Materials Science |
Том | 27 |
Номер выпуска | 1-2 |
DOI | |
Состояние | Опубликовано - мар 2003 |
ID: 17373503