F–H···N hydrogen bonds: Influence of substituent and hybridization of nitrogen on H-bond properties and two-bond 19F–15N spin–spin coupling constants (2hJF–N)

The effects of substituent and hybridization of nitrogen atom on hydrogen bonding in the F–H···NCX, F–H···N(H)CX, and F–H···N(H)2–CX complexes have theoretically been studied by MP2 and DFT methods with aug-cc-pVDZ and 6-311++G∗∗ basis sets. With respect to the hybridization of nitrogen, sp3-hybridized nitrogen forms the strongest bond, followed by sp2 and then sp. In equilibrium structures, the trend in the two-bond 19F–15N spin–spin coupling constants (2hJF–N) is sp < sp3 < sp2. The results of atoms in molecules (AIM) and natural bond orbital (NBO) analyses are in meaningful relationships with other characteristics of hydrogen bonds, especially with the 2hJF–N values.