Halogen–halogen interaction in view of many-body approach

The many-body theory was applied in order to estimate the character of interaction in quadruple complex consisting of four bromomethane molecules. The tetrameric complex used as a model system was found in the crystal structure in which halogen bonds were stabilizing the solid state structure. Decomposition of interaction energy on two-, three- and four-body terms allowed to conclude that individual halogen bonds in tetramer rather does not cooperate forming the complex. The nonadditive contribution to interaction energy is negative, but of very small value in respect to total interaction energy (less than 0.01%), indicating very weak cooperativity of halogen bridges.