Analysis of the oxalamide functionality as hydrogen bonding former:: geometry, energetics, cooperative effects, NMR chemical characterization and implications in molecular engineering

The oxamide(...)oxamide interactions are examined in this study. The geometry and energetics of such interactions are explored with ab initio and density functional methods. Furthermore, the cooperative effects and the influence of intermolecular interactions in NMR chemical shifts are investigated through density functional calculations. Results are compared with those obtained for the amide(...)amide interaction. Calculations are performed for bimolecular and trimolecular complexes of N,N'-dimethyloxalamide and N-methylacetamide, which are used as model compounds. The results reported here provide a basis to discuss the role of the oxamide functionality in molecular engineering. (C) 2004 Elsevier B.V. All rights reserved.