Halogen bond versus hydrogen bond: The many‐body interactions approach

Abstract

Abstract The analysis of interrelation between halogen bond and hydrogen bond in the (RX)(HNC)(HCN) complexes (R = CH 3 , CF 3 and X = Cl, Br, I) was performed on the basis of DFT calculations. Both two‐body additive contributions and three‐body nonadditive contributions to the total interaction energy were discussed. QTAIM was used for topological analysis of electron density. Additionally, QTAIM analysis of electron density was performed for both two‐ and three‐body complexes. The electron charge transfer in trimers showed the dual character of the fragment with halogen atom involved into the investigated interactions—it acts as Lewis acid and Lewis base, depending on the type of interaction considered. The effect of cooperativity of X‐ and H‐bonding was assessed on the basis of many‐body interaction energy and electron density analysis. Additionally, an alternative two‐body model with the same situation (in the context of intermolecular interactions) is investigated. The anti‐cooperative effect was found also for this model.