Competing patterns of weak directional forces in pressure-frozen CH2ClI and CH2I2

lsostructural relations and phase transitions of dihalomethanes have been rationalized by the competing patterns of CH center dot center dot center dot halogen hydrogen bonds and halogen center dot center dot center dot halogen interactions, the common weak directional interactions in soft organic matter. Pressure-frozen chloroiodomethane, CH2ClI, at 295 K and 0.72 GPa forms centrosymmetric phase III, which at ca. 400 K and 1.6 GPa disproportionates into CH2Cl2 and CH2I2. The directional character of intermolecular contacts between halogen atoms results from the characteristic anisotropic charge distribution on molecular surface.