Cooperativity between the halogen bonding and halogen–hydride bonding in NCX⋯NCX⋯HMgY complexes (X = F, Cl, Br; Y = H, F, Cl, Br, CH3, Li)

Cooperativity between the intermolecular interactions has attracted more interest of scientists recently due to the wide use of them in molecular recognition, crystal engineering and biological systems. In this paper, the NCX⋯NCX⋯HMgY triads (X = F, Cl, Br; Y = H, F, Cl, Br, CH3, Li) were constructed to investigate the cooperativity between the halogen and halogen–hydride bonds by quantum chemical calculations. To understand the properties of the systems better, the corresponding dyads are also studied. It is found that the intermolecular distances in the triads, except some of the ternary NCF⋯NCF⋯HMgY complexes, are always smaller than the corresponding values in the binary systems. All complexes show cooperative energy ranging from −0.08 to −0.32 kJ/mol, −0.56 to −1.82 kJ/mol and −1.11 to −3.61 kJ/mol for X = F, Cl and Br, respectively (at MP2/6-311++G(d,p) level). These results indicate significant cooperativity between the halogen and halogen–hydride bonds in these complexes. A many body analysis approach is used to study the two- and three-body contributions in the total interaction energy of complexes. Many-body analysis shows that all the two- and three-body interaction energies are attractive in all triads and make a positive contribution to the total interaction energy. The nature of interactions of the complexes is analyzed using parameters derived from the molecular electrostatic potential (MEP), atoms in molecules (AIM), electron localization function (ELF) and natural bond orbital (NBO) methodologies.