Deuterium isotope effects on P-31 NMR parameters: Hydrogen bonding in a solid urea phosphoric acid adduct

Long-range deuterium isotope effects on the P-31 NMR shielding tensor were studied for the perdeuteriated urea-phosphoric acid adduct (ND2)(2)CO . D3PO4. This complex contains a short hydrogen bond linking its molecular components, for which a single-minimum potential energy well has been suggested. The results indicate that (sigma(11) - sigma(iso)) decreases and (sigma(33) - sigma(iso)) increases for the deuteriated complex with respect to the undeuteriated adduct. This fact is consistent with the hypothesis of a single-minimum potential energy surface for the short hydrogen bond.