Information Table for full results). Whilst PBE0 and SAOP calculations with B3LYPHF20-50 hybrid-functionals have also provided good correlation of C, N, Si and 31 P NMR parameters when these atoms are bonded to f-block ions; B3LYPHF50 was previously found to be optimal for predicting chemical shifts of thoriumbound phosphorus atoms. In this case, optimization of H-positions gave the best agreement with experiment (Table ). B3LYPHF20, corresponding to Becke's popular three-parameter fit of the hybrid exchangecorrelation functional, achieved close agreement with the experimental isotropic shifts, but the span of the anisotropy was larger than that observed experimentally (in all calculations, see Table ) and the predicted skew was more negative. However, these were of the correct order of magnitude and the skew had the correct sign. Selecting the optimal Hartree-Fock exchange contribution to best match the experimental solid-state isotropic shift suggested 30%.