“…1 There are some well-known methodologies for the evaluation of the cooperativity of noncovalent bonds and the calculation of related cooperative energies. The following equations have been frequently used for the evaluation of the cooperativity of coinage-metal bonds with other types of interactions 2–13 and also that of intermolecular noncovalent bonds, especially those including hydrogen bonds, 14–25 dihydrogen bonds, 26–28 beryllium bonds, 29,30 lithium bonds, 31–34 lithium–π, 35 halogen bonds, 36–48 chalcogen bonds, 49–51 pnicogen bonds, 52–56 cation–π interactions, 57–60 anion–π interactions, 61–63 π⋯π interactions, 64 σ -hole 65,66 and π -hole 67–70 interactions in ternary systems. Δ ABC = IE total ABC − (IE ABC A–B + IE ABC B–C + IE ABC A–C ) E coop = SE ABC − (SE AB + SE BC + SE ABC AC ) E coop = SE ABC − (SE AB + SE BC )In the above equations, Δ ABC and E coop correspond to the three-body term 71–77 and cooperative energy, respectively. The term IE total ABC is used for the value of the total interaction energy of the ABC system, and the terms IE ABC AB , IE ABC BC and IE ABC AC are used for pairwise interaction energies in the structure of the ABC system.…”