Halogen Bonding of Organoiodines and Triiodide Anions in (NMe₃Ph)⁺ Salts

Abstract

To study the role of the triiodide (I 3 ) À anion in establishing various halogen bonding patterns, the trimethylphenylammonium iodide (NMe 3 PhI) salt was reacted with diiodine (I 2 ) in the presence of a series of organoiodines, tetraiodoethylene (TIE), 1,2-diiodo-3,4,5,6-tetrafluorobenzene (o-F 4 DIB), 1,4-diiodo-2,3,5,6-tetrafluorobenzene (p-F 4 DIB), and 1,3,5-trifluoro-2,4,6-triiodobenzene (1,3,5-F 3 I 3 B) to form cocrystals of the organoiodines with the trimethylphenylammonium triiodide (NMe 3 PhI 3 ) salt. Single-crystal X-ray crystallography revealed the (I 3 ) À anion served as a halogen bond acceptor for the organoiodine donors, forming a variety of 1-D, 2-D, and 3-D packing arrangements through I•••I halogen bonding. Significant asymmetry was observed within the (I 3 ) À anion. The melting points of the cocrystalline materials, as determined by simultaneous DSC/TGA, ranged from 43°C to 119°C and showed a strong dependence on the identity of the organoiodine incorporated into the crystal lattice.