1-Chloro-4-[2-(4-chloro­phen­yl)eth­yl]benzene and its bromo analogue: crystal structure, Hirshfeld surface analysis and computational chemistry

The crystal and mol­ecular structures of C(14)H(12)Cl(2), (I), and C(14)H(12)Br(2), (II), are described. The asymmetric unit of (I) comprises two independent mol­ecules, A and B, each disposed about a centre of inversion. Each mol­ecule approximates mirror symmetry [the C(b)—C(b)—C(e)—C(e) torsion angles = −83.46 (19) and 95.17 (17)° for A, and −83.7 (2) and 94.75 (19)° for B; b = benzene and e = ethyl­ene]. By contrast, the mol­ecule in (II) is twisted, as seen in the dihedral angle of 59.29 (11)° between the benzene rings cf. 0° in (I). The mol­ecular packing of (I) features benzene-C—H⋯π(benzene) and Cl⋯Cl contacts that lead to an open three-dimensional (3D) architecture that enables twofold 3D–3D inter­penetration. The presence of benzene-C—H⋯π(benzene) and Br⋯Br contacts in the crystal of (II) consolidate the 3D architecture. The analysis of the calculated Hirshfeld surfaces confirm the influence of the benzene-C—H⋯π(benzene) and X⋯X contacts on the mol­ecular packing and show that, to a first approximation, H⋯H, C⋯H/H⋯C and C⋯X/X⋯C contacts dominate the packing, each contributing about 30% to the overall surface in each of (I) and (II). The analysis also clearly differentiates between the A and B mol­ecules of (I).