Density functional theory study of N–H⋯O, O–H⋯O and C–H⋯O hydrogen-bonding effects on the 14N and 2H nuclear quadrupole coupling tensors of N-acetyl-valine Original Research Article

Hydrogen-bonding effects in the crystalline structure of N-acetyl-valine, NAV, were studied using the 14N and 2H quadrupole coupling tensors via density functional theory. The calculations were carried out at the B3LYP level with the 6-311++G(d,p) and 6-311+G(d) basis sets. The theoretical quadrupole coupling components and their relative orientation in the molecular frame axes at the nitrogen site are compared to experimental values. This nucleus is involved in a rather strong intermolecular Odouble bond; length as m-dashCNH⋯Odouble bond; length as m-dashCNH hydrogen bond, rN–H⋯O(1) = 2.04 Å and ∠N–H⋯O(1) = 171.53°. A reasonably good agreement between the experimentally obtained 2H quadrupole coupling tensors and the B3LYP/6–311++G(d,p) calculations is achievable only in molecular model where a complete hydrogen-bonding network is considered.