A B3LYP and MP2 theoretical investigation into the synergetic effect between the O/NH⋯O and O/NH⋯F− anionic hydrogen-bonding interactions in N-(Hydroxymethyl)acetamide complex with F−

The synergetic effects between the O/NH⋯F− anionic hydrogen-bonding and conventional O/NH⋯O hydrogen-bonding interactions in the 1:2 (F−:N-(Hydroxymethyl)acetamide) ternary systems are investigated at the B3LYP/6-311++G** and MP2/6-311++G** levels. The non-additivity energies are also calculated. The result shows that the distance RF⋯H of the NH⋯F− H-bond in the ternary system is shortened greatly in comparison with that in the binary complex. The O/NH⋯O H-bonding interaction is increased due to the presence of the O/NH⋯F− H-bond upon ternary-system formation. Furthermore, the increase of the H⋯O interaction in the OH⋯OH, NH⋯OH or NH⋯OC link is more notable than that in the OH⋯OC contact. The synergetic effect is found in the conformation formed by the O/NH⋯F− and O/NH⋯O interactions, while the anti-synergetic effect is present in the complex where only the O/NH⋯F− H-bond is found and the O/NH⋯O H-bond is broken in going from the binary to ternary complex. Shift of electron density confirms the existence of cooperativity.