NMR RESOLUTION OF A CRYSTALLOGRAPHIC CONTROVERSY - N-14 SINGLE-CRYSTAL STUDIES OF SILVER, BARIUM, AND LEAD NITRATES

14N single-crystal nuclear magnetic resonance studies of the nitrates of lead, silver, and barium have shown that, in all three cases, the unit cell has a center of symmetry, thus resolving a controversial issue in the crystallographic literature. The quadrupolar coupling constants of the nitrates are relatively small and show a wide variation, attributed to near-cancellation of opposing contributions from the intramolecular and intermolecular parts of the electric field gradient tensor. The chemical shielding tensors are very similar to each other and to those of previously reported nitrates. The orientations of the nitrate quadrupolar and chemical shielding tensors are as predicted from the local symmetry, with the unique axes perpendicular to the plane of the anion in both cases. No evidence for significant static or dynamical disorder is observed. © 1990 American Chemical Society.