Structure of the mercury(II) mixed-halide (Br/Cl) complex of 2,2′-(5-tert-butyl-1,3-phenyl­ene)bis­­(1-pentyl-1H-benzo[d]imidazole)

The mercury(II) complex of 2,2′-(5-tert-butyl-1,3-phenyl­ene)bis­(1-pentyl-1H-benz­imidazole), namely catena-poly[dihalogenido­mercury(II)]-μ-2,2′-(5-tert-butyl-1,3-phenyl­ene)bis­(1-pentyl-1H-benzimidazole)-κ2N3:N3′], [HgBr1.52Cl0.48(C34H42N4)], 2, has a polymeric structure bridging via the N atoms from the benzimidazole moieties of the ligand. The compound crystallizes in the ortho­rhom­bic space group Pca21 and is a racemic twin [BASF = 0.402 (9)]. The geometry around the HgII atom is distorted tetra­hedral, with the HgII atom coordinated to two N atoms, one Br atom, and a fourth coordination site is occupied by a mixed halide (Br/Cl). For the two ligands in the asymmetric unit, there is disorder with one of the two tert-butyl groups and benzimidazole moieties showing twofold disorder, with occupancy factors of 0.57 (2):0.43 (2) for the tert-butyl group and 0.73 (3):0.27 (3) for the benzimidazole group. In addition, there is threefold disorder for two of the four n-pentyl groups, with occupancy factors of 0.669 (4):0.177 (4):0.154 (4) and 0.662 (4):0.224 (4):0.154 (4), respectively. The mol­ecules form a one-dimensional helical polymer propagating in the b-axis direction. The helices are held together by intra-strand C—H⋯Br and C—H⋯Cl inter­actions. Each strand is further linked by inter-strand C—H⋯Br and C—H⋯Cl inter­actions. In addition, there are weak C—H⋯N inter-strand inter­actions which further stabilize the structural arrangement.