To better understand the anionic substructure of ReO 3 -type TiOF 2 , we consider the pair-distribution function obtained from X-ray total scattering data. For interatomic distances between 8 Å and 40 Å, the PDF data are well described by a cubic P m 3m model (R w = 13.2 % (Fig. ), in agreement with the X-ray diffraction analysis above. The experimental PDF for r < 8 Å, however, gives a poor fit (R w = 31.2 %) when modelled with a cubic ReO 3 -type (P m 3m) structure (Fig. ), indicating deviations from the average ReO 3 -type structure at short range. Notably, we observe apparent splittings in the nearest-neighbour Ti-X peak at ∼ 1.9 Å and in the next-nearest-neighbour peak at ∼ 3.8 Å, suggesting distinct bonding environments. Based on the expectation that Ti-O bonding will, in general, be stronger than Ti-F bonding , we preliminarily assign the peaks at 1.71 Å and 1.94 Å to Ti-O and Ti-F nearest-neighbour pairs, respectively, and the peaks at 19 F MAS (64 kHz) NMR spectrum (Fig. ). Averaging over lines 1 and 2 gives a weighted average for bridging Ti-F-Ti environments ⟨δiso⟩ = 17.6 ppm.