Examination of the PDOS for rhombohedral NbO0.3F2.7 and NbF3 (Fig. ) shows an additional in the niobium 3d states absent at higher oxygen compositions. This is caused by the trigonal distortion of the octahedra discussed previously (Fig. ) with the effect that the cubic 3d t2g states are split into a combination of occupied eg and unoccupied a1g states. The resulting electronic gap (0.9 eV) allows NbF3 to maintain spin polarisation whilst being semiconducting, and contrasts with previous predictions of half-metallic behaviour for x = 2.