Molecular Structure of Hexakis(dichloromethyl)benzene

The crystal and molecular structure of hexakis(dichloromethyl)benzene (2) has been determined. Crystals of 2 are triclinic, space group PI: a = 6.248 (1) Å, b = 9.749 (3) Å, c = 9.763 (2) Å, a = 116.32 (2)°, β = 94.97 (2)°, ϒ = 108.20 (2)°, Z = 1. The crystal structure and the dimensions of the unit cell closely resemble those previously found for hexaisopropylbenzene (1), and the molecules of 2, like those of 1, closely approximate C_6h symmetry in the crystal. A crystallographic orientational disorder was resolved, and the population ratio of major and minor orientations, 1.827, was found to be similar in magnitude to the corresponding ratio for 1, 2.075. Empirical force-field calculations have revealed that in contrast to l,2-bis(dichloromethyl)- and pentakis(dichloromethyl)benzene, the conformations of lowest energy in 1,2-diisopropyl- and pentaisopropylbenzene are not gear-meshed and that 1 is unique among vicinally substituted polyisopropylbenzenes in having a ground-state conformation with homodirectional isopropyl groups.