The geometry, interaction energy and bonding properties of ternary complexes O3Z···NCX···NCY (Z= Kr, Xe; X = Cl, Br, I and Y=H, F, OH) are investigated with ab initio calculations at the MP2/aug-cc-pVTZ level. Two different types of intermolecular interactions are present in these complexes, namely, aerogen bond (Z···N) and halogen bond (X···N). The formation mechanism and bonding properties of these complexes are analyzed with molecular electrostatic potentials, quantum theory of atoms in molecules and non-covalent interaction index. It is found that the cooperativity energies in the ternary complexes are all negative; that is, the interaction energy of the ternary complex is greater than the sum of the interaction energies of the corresponding binary systems. Also, the cooperativity energies increase with the increase of the interaction energies. The cooperative effects in the ternary complexes make a decrease in the total spin-spin coupling constants across the aerogen bonding, J(Z–N), which can be regarded as a proof for the reinforce of Z•••N interactions in the ternary complexes with respect to the binary systems.
