Crystal structure of tetra­butyl­ammonium bromide–1,2-di­iodo-3,4,5,6-tetra­fluoro­benzene–di­chloro­methane (2/2/1)

The crystallization of a 1:1 molar solution of 1,2-di­iodo-3,4,5,6-tetra­fluoro­benzene (o-DITFB) and tetra­butyl­ammonium bromide (n-Bu(4)NBr) from di­chloro­methane yielded pure white crystals of a halogen-bonded compound, C(16)H(36)N(+)·Br(−)·C(6)F(4)I(2)·0.5CH(2)Cl(2) or [(n-Bu(4)NBr)(o-DITFB)]·0.5CH(2)Cl(2). The compound may be described as a quaternary system and may be classified as a salt–cocrystal solvate. The asymmetric unit contains one mol­ecule of solvent, two o-DITFB mol­ecules, two cations (n-Bu(4)N(+)) and two crystallographically distinct bromide ions [θ(I) (⋯) (Br-) (⋯) (I) = 144.18 (1) and 135.35 (1)°]. The bromide ion is a bidentate halogen-bond acceptor which inter­acts with two covalently bonded iodines (i.e. halogen-bond donors), resulting in a one-dimensional polymeric zigzag chain network approximately along the a axis. The observed short contacts and angles are characteristic of the non-covalent inter­action [d (C—I⋯Br) = 3.1593 (4)–3.2590 (5) Å; θ(C—I⋯Br) = 174.89 (7) and 178.16 (7)°]. It is noted that iodine acts as both a halogen-bond donor and a weak CH hydrogen-bond acceptor, while the bromide ions act as acceptors for weak CH hydrogen bonds and halogen bonds.