8. Crystal structure of tetraethylammonium chloride 3,4,5,6-tetrafluoro-1,2-diiodobenzene
   Viger-Gravel, J.; Korobkov, I.; Bryce, D. L.
   Acta Crystallogr., Sect. E: Crystallogr. Commun. 2015, 71, o319-o320

Equimolar qu­anti­ties of tetra­ethyl­ammonium chloride (Et₄NCl) and 3,4,5,6-tetra­fluoro-1,2-di­iodo­benzene (o-DITFB or o-C₆F₄I₂) have been co-crystallized in a solution of di­chloro­methane yielding a pure halogen-bonded compound, 3,4,5,6-tetra­fluoro-1,2-di­iodo­benzene-tetra­ethyl ammonium chloride (2/1), Et₄N⁺·Cl^-·2C₆F₄I₂, in the form of translucent needles. [(Et₄NCl)(o-C₆F₄I₂)₂] packs in the C2/c space group. The asymmetric unit includes one mol­ecule of DITFB, one Et₄N⁺ cation located on a twofold rotation axis, and one chloride anion also located on a twofold rotation symmetry axis. This compound has an inter­esting halogen-bonding environment surrounding the halide. Here, the chloride anion acts as a tetra­dentate halogen bond acceptor and forms a distorted square-pyramidal geometry, with ICl^-I angles of 80.891 (6) and 78.811 (11)°, where two crystallographically distinct iodine atoms form halogen bonds with the chloride anion. Resulting from that square-pyramidal geometry are short contacts between some of the adjacent F atoms. Along the b axis, the halogen-bonding inter­action results in a polymeric network, producing a sheet in which the two closest chloride ions are 7.8931 (6) Å apart. The Et₄N⁺ cation alternates in columns with the halide ion. The expected short contacts (shorter than the sum of their van der Waals radii) are observed for the halogen bonds [3.2191 (2) and 3.2968 (2) Å], as well as almost linear angles [170.953 (6) and 173.529 (6)°].

DOI : 10.1107/S205698901500732X