A DFT and AIM analysis of the spin-spin couplings across the hydrogen bond in the 2-fluorobenzamide and related compounds
In 1975 a large number of coupling constants were measured in 2-fluorobenzamide labeled with 15N. Some of them were assigned to couplings through intramolecular NH···F hydrogen bonds (HBs). These couplings change dramatically when CDCl3 is replaced by DMSO-d6. In this theoretical paper we provide density functional theory (DFT) calculations that justify the existence of a weak HB in the absence of solvent, while solvents that act as HB acceptors break down the intramolecular hydrogen bond (IMHB) of 2-fluorobenzamide. Atoms in molecules (AIM) analyses and Steiner-Limbach plots were used to analyze the structure of the compounds.