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

Abstract

Long-range deuterium isotope effects on the ³¹P NMR shielding tensor were studied for the perdeuteriated urea–phosphoric acid adduct (ND₂)₂CO · 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 (σ₁₁–σ_iso) decreases and (σ₃₃–σ_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.