Absence of halogen...halogen interactions in chlorotrimethylsilane polymorphs

The structures of in situ pressure-frozen chlorotrimethylsilane crystals, (CH3)3SiCl, have been determined at 0.23, 0.30 and 0.58 GPa. The molecular arrangements in the low-temperature and high-pressure phases are two-dimensionally isostructural, but different in the third perpendicular direction. Consequently, a striking similarity exists between the unit-cell dimensions of these polymorphs. The absence of short Cl...Cl contacts, both in the low-temperature or pressure-frozen phases of (CH3)3SiCl, has been rationalized in terms of the favoured packing patterns and comparable energies of halogen...halogen interactions and other van der Waals forces.