Pressure-frozen 1,2,3-trichloropropane.

The structure of 1,2,3-trichloropropane, ClCH2CHClCH2Cl, in-situ crystallized in a diamond-anvil cell, has been determined by single-crystal X-ray diffraction at 0.28 and 0.35 GPa. A melting point at 295 K and 0.22 GPa has been determined. The molecular conformation of aliphatic chain and terminal Cl atoms is approximately C2 symmetric. Of the intermolecular contacts, the tightest are the Cl...Cl and then the Cl...H contacts, whereas the H...H distances are considerably longer than the sum of the van der Waals radii and leave narrow voids in the structure. The elevated pressure reduces the H...H separations but hardly affects the Cl...Cl distances. The crystal growth rates, compression and types of intermolecular interactions in the structures can be correlated with the directions of the Cl...Cl contacts, which can be considered the main motif responsible for the molecular arrangement in the structure.