Abstract
The crystallization of a 1:1 molar solution of 1,2-diiodo-3,4,5,6-tetrafluorobenzene (o-DITFB) and tetrabutylammonium bromide (n-Bu4NBr) from dichloromethane yielded pure white crystals of a halogen-bonded compound, C16H36N+-Br-center dot C6F4I2-0.5CH(2)Cl(2) or [(n-Bu4NBr)(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-Bu4N+) and two crystallographically distinct bromide ions [theta I center dot center dot center dot Bu-center dot center dot center dot I = 144.18 (1) and 135.35 (1)degrees]. 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 [dc-(I center dot center dot center dot Br) = 3.1593 (4)-3.2590 (5) angstrom; theta(C-I center dot center dot center dot Br) = 174.89 (7) and 178.16 (7)1. 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.