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 C₁₄H₁₂Cl₂, (I), and C₁₄H₁₂Br₂, (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). [ABSTRACT FROM AUTHOR]