First principles NMR calculations of phenylphosphinic acId C(6)H(5)HPO(OH). Assignments, orientation of tensors by local field experiments and effect of molecular motion

The complete set of NMR parameters for 17 0 enriched phenylphosphinic acid C6H5HP*O(*OH) is calculated from first principles by using the Gauge Including Projected Augmented Wave (GIPAW) approach [C.J. Pickard, F. Mauri, All-electron magnetic response with pseudopotentials: NMR chemical shifts, Phys. Rev. B 63 (2001) 245101/1-245101/13]. The analysis goes beyond the successful assignment of the spectra for all nuclei (H-1, (13)c, O-17, P-31), as: (i) the 1H CSA (chemical shift anisotropy) tensors (magnitude and orientation) have been interpreted in terms of H bonding and internuclear distances. (ii) CSA/dipolar local field correlation experiments have allowed the orientation of the direct P-H bond direction in the (31)p CSA tensor to be determined. Experimental and calculated data were compared. (iii) The overestimation of the calculated 31p CSA has been explained by local molecular reorientation and confirmed by low temperature static 1H -> (31)p, CP experiments. (C) 2007 Elsevier Inc. All rights reserved