Triangular halogen-halogen-halogen interactions as a cohesive force in the structures of trihalomesitylenes

The structures and molecular packing of tribromo- and triiodomesitylene are reported and compared to that of trichloromesitylene. Attractive triangular X-3 interactions dominate the molecular packing in all three structures. The nonspherical atomic charge distribution on the halogens results in the formation donor-acceptor interactions in which each halogen atom is simultaneously a donor and an acceptor. These triangular X-3 (X = Br or I) interactions result in the formation of 2-dimensional sheetlike structures.