Using a combination of DFT calculations and cluster expansion modelling, we predict strong short-range ordering in ReO 3 -type TiOF 2 , characterised by an absence of collinear O-Ti-O units and a preference for polar cis-TiO 2 F 4 titanium coordination. This polar coordination around titanium allows shorter Ti-O bonds and longer Ti-F bonds relative to the conventional P m 3m structure, which gives increased net bonding relative to trans-TiO 2 F 4 titanium coordination. The preferential cis-TiO 2 F 4 coordination also results in correlated anion disorder , which gives uncorrelated anion siteoccupations at longer distances, in agreement with the average P m 3m structure assigned from long-length-scale diffraction data .