Intramolecular HB Interactions Evidenced in Dibenzoyl Oxalamide Derivatives: NMR, QTAIM, and NCI Studies.

Extensive NMR spectroscopic studies revealed information on the occurrence of bifurcated intramolecular hydrogen bond in the dibenzoyl oxalamide derivatives. One-dimensional NMR experiments, viz., solvent dilution, temperature perturbation, and two-dimensional experimental techniques, such as N-H HSQC and F-H HOESY, have been exploited to derive unambiguous confirmation of the participation of organic fluorine in the hydrogen-bonding interaction. The experimental NMR findings have been ratified by density functional theory based calculations, viz., NCI (noncovalent interaction) and QTAIM (quantum theory of atoms in molecules).