The asymmetry and width of the main peak in the 19 F NMR spectrum suggest that our ReO 3 -type TiOF 2 sample contains multiple distinct fluoride-ion environments. Previous studies have reported that TiOF 2 prepared by aqueous solution synthesis contains hydroxyl defects and metal vacancies . The relative intensities of the fitted 19 F NMR resonances (Table ) indicate that only 2.2 % of F -ions are "non-bridging" in our sample, implying a relatively high stoichiometric purity, with a Ti vacancy concentration of ≲ 0.5 % . This low Ti-vacancy concentration is insufficient to explain the asymmetry and breadth of the main peak in the 19 F NMR data. Instead, we interpret these features as indicative of O/F disorder, which is expected to produce a range of local fluoride-ion environments and a corresponding distribution of Ti-F bond lengths.