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

Hydrogen-bonding effects in the crystalline structure of N-acetyl-valine, NAV, were studied using the N-14 and H-2 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 O=CNH center dot center dot center dot O=CNH hydrogen bond, r(N-H center dot center dot center dot O(1))=2.04 angstrom and angle N- H center dot center dot center dot O(1)= 171.53 degrees. A reasonably good agreement between the experimentally obtained H-2 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. (c) 2007 Elsevier B.V. All rights reserved.