Halogen bonding between substituted chlorobenzene and trimethylamine: Decisive role of σ–hole and CCl bond breaking energy

Abstract

AbstractTheoretical studies have been carried out on the halogen bonding interaction between para substituted chlorobenzene (YC6H4Cl, Y = H, NH2, CH3, F, CN, NO2) and N(CH3)3 using ab initio MP2/aug‐cc‐pVDZ and DFT based wB97XD/6‐311++G(d,p) methods. The positive electrostatic potential (VS,max) on the Cl atom and the heterolytic bond breaking enthalpy of the CCl bond have been calculated and their role on halogen bonding is discussed. The heterolytic bond breaking enthalpy of the CCl bond is proposed as a measure of the strength of the σ‐hole on Cl atom. The binding strength of the complexes ranging between −6.13 kJ mol−1 and −9.29 kJ mol−1 are linearly related to the VS,max of the Cl atom and the bond breaking enthalpy of the CCl bond. In addition, energy decomposition analysis was performed on the halogen bonded complexes via symmetry adapted perturbation theory (SAPT) to predict the dominant energy component and the nature of the N···Cl interaction.