Synthesis, spectroscopic and structural characterization of novel interaction product of 5-trifluoromethyl-pyridine-2-thione with iodine

The behavior of 5-trifluoromethyl-pyridine-2-thione, which is a potential antithyroid drug, toward molecular iodine was investigated. The formation of the n–σ* complex of 5-trifluoromethyl-pyridine-2-thione with molecular iodine of the composition C6H4F3NS·I2 in dilute chloroform solutions was studied by UV-spectroscopy. The crystal structure of the new salt bis(5-trifluoromethyl-pyridine-2-ylthio)iodonium triiodide determined by X-ray diffraction and consists of separated, perfectly linear, centrosymmetrical anions I3- and cationic moieties (C6H3F3NS)2I+ containing the almost linear S–I+–S linker. Iodonium cations are linked to dimers through the I(4)–I(5)–I(4′) anion by means of N-H⋯I, C–H⋯I hydrogen bonds (N(1)–H(1А)⋯I(4) 3.11 Å, N(2)–H(2B)⋯I(4) 2.99 Å, C(5)–H(5A)⋯I(5) 3.05 Å), interatomic distance I(1)⋯I(4) 4.2040(7) Å. These dimers are linked into layers parallel to the ab0 plane by short intermolecular contacts I(1 M)⋯S(1) 3.850(2) Å, I(1)⋯I(1 M) 3.9326(8) Å.