The precursor decomposition followed a sigmoidal shape, suggesting an auto-catalytic mechanism. In addition, the reaction rate depended on the ratio of TiCl 4 and Ti(O i Pr) 4 , with higher reaction rates (and shorter induction times) for higher contents of TiCl 4 . Later, when titania nanocrystals were grown in TOPO at 300 • C from titanium halides and various titanium alkoxides, 15 the reaction rate was reported to increase with the branching of the alkoxide (Me < Et < i Pr < t Bu), consistent with an S N 1 (or E1) mechanism.