The previously published structural and AIMD studies of these systems O shift lying closer to that of the position of the O V resonance than would be expected purely from stoichiometry implies the presence of over-coordinated V sites, with the average O environment residing more frequently near V. These results agree with the 51 V resonances measured between -450 and -510 ppm (Figure ), which are consistent with both 4-and 5-coordinate vanadium environments observed previously, as well as a change towards more highly-coordinated V sites (higher frequency V shifts) at higher temperatures; we do however note that the isotropic V shifts are difficult to fully resolve at the slow spinning speeds used in the VT-NMR experiments.