For NbO2F, the structural transition to a rhombohedral phase with pressure has no significant impact on the electronic properties. The phase remains semiconducting with a large band gap between the oxygen 2p and niobium 3d states (Fig. ), although the band gap does show a slight increase (less than 1 eV) with pressure. Additionally, the octahedral splitting in the Nb 3d band is more pronounced for the rhombohedral structure. These effects are due to narrowing of the 3d bands due to the octahedral tilting, caused by the reduced overlap efficiency between niobium 3d t2g and anion 2p states. This is supported by an observed increase in the octahedral splitting with octahedral rotation. The most significant observation from the phase diagram (Fig. ) is the co-occurrence of the transition between metallic and half-metallic behaviour with the cubic to rhombohedral phase transition, observed for compositions around x = 0.35 and pressures of 3-5 GPa. This can be understood by comparing the density of states for each symmetry for x = 0.35 (Fig. ). Increased narrowing of the minority spin 3d bandwidth in the rhombohedral phase causes it to become unoccupied, resulting in a half-metallic state. In contrast, the broader cubic 3d band (driven by more effective overlap between Nb and O orbitals) causes it to be partially occupied, maintaining a metallic state.