Investigation hydrogen-bonding capabilities of modified amide groups using calculated nuclear quadruple coupling constants

Nuclear quadrupole coupling constants, chis, for 17 chemical species are calculated. These are retroamide, N-hydroxamide, A-amino amide, thioamide, methylamine and complexes which amide generates with retroamide and other modified amides. The charge distributions around quadrupolar nuclei are most affected upon intermolecular hydrogen bond formations. chis of these nuclei are computed using ab initio calculations. Some of our findings for average values of chis of H-2, N-14 and O-17 in hydrogen bonds are 200.00 kHz, 4.40 MHz and 10.50 MHz, respectively. There is a fairly linear dependency between R-O...(H) and the logarithm of H-2 chis. This correlation is approximately linear for O-17 and N-14 nuclei. (C) 2003 Elsevier Science B.V. All rights reserved.