Abstract
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 I⋯Cl−⋯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)°].
Highlights
Abate et al discuss applications in crystal engineering. The latter reports describe the usefulness of solid-state nuclear magnetic resonance to characterize these types of halogen-bonding environments (Viger-Gravel, Leclerc et al, 2014; VigerGravel, Meyer et al, 2014)
Et4N+ cation located on a twofold rotation axis, and one chloride anion located on a twofold rotation symmetry axis
The chloride anion acts as a tetradentate halogen bond acceptor and forms a distorted square-pyramidal geometry, with I Cl I angles of 80.891 (6) and 78.811 (11), where two crystallographically distinct iodine atoms form halogen bonds with the chloride anion
Summary
The crystal structure of 3,4,5,6-tetrafluoro-1,2-diiodobenzene has been recently published by our group (Viger-Gravel, Leclerc et al, 2014) and the crystal structure of Et4NCl was reported by Staples (1999). Reports by Abate et al (2009), and our previous work (Viger-Gravel, Leclerc et al, 2014; VigerGravel, Meyer et al, 2014; Viger-Gravel et al, 2015) may be consulted for other similar halogen-bonded compounds containing o- or p-DITFB and ammonium halide salts. Abate et al discuss applications in crystal engineering.
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