Reaction of N-methylbenzothiazole-2-thione (C8H7NS2 or NMBZT) with diiodine produced the charge-transfer (ct) complex [(NMBZT).I2] (1). NMBZT reacts with diiodine in the presence of FeCl3 in a molar ratio of 3:6:1 and forms the ionic complex [[(NMBZT)2I+].[FeCl4]-] (2) together with [[(NMBZT)2I+].[I7]-] (2a) iodonium salt. The reaction of benzimidazole-2-thione (C7H6N2S or MBZIM) with diiodine on the other hand results in the formation of the ct [[(MBZIM)2I]+[I3]-].[(MBZIM).I2] (3) compound. The compounds have been characterized by elemental analyses, DTA-TG, FT-Raman, FT-IR, UV-vis, and 1H NMR spectroscopies, and X-ray crystal structure determinations. Compound 1, C8H7I2NS2, is orthorhombic with a space group Pna2(1) and a = 12.5147(13) angstroms, b = 22.536(3) angstroms, c = 4.2994(5) angstroms, and Z = 4. Compound 2, C16H14Cl4FeIN2S4, is monoclinic, space group C2/c, a = 35.781(2) angstroms, b = 7.4761(5) angstroms, c = 18.4677(12) angstroms, beta = 107.219(1) degrees, and Z = 8. Compound 3, C21H18I6N6S3, monoclinic, space group P2(1)/n, a = 14.0652(11) angstroms, b = 22.536(3) angstroms, c = 4.2994(5) angstroms, beta = 99.635(7) degrees, and Z = 4, consists of two component moieties cocrystallized, one neutral which contains the benzimidazole-2-thione (MBIZM) ligand bonded with an iodine atom through sulfur, forming a compound with a "spoke" structure [(MBZIM)I2] 3a, while the other is the ionic complex [[(MBZII)2I+].[I3]-] (3b). The X-ray crystal structure of 1 shows a bond between the thione-sulfur atom and one of the iodine atoms in an essentially planar arrangement. In the cation of 2, an iodine is coordinated by two thione-sulfur atoms in a linear arrangement but the molecule is not planar. For the first time in the solid state a spoke-ionic mixed complex has been characterized in 3. One component of the structure is a molecular diiodine adduct, i.e., [(MBZIM)I2] (3a), with a linear coordination geometry in a decidedly planar arrangement, and the other component is an ionic adduct [[(MBZIM)2I]+.[I3]-] (3b) with the cation having an arrangement similar to that found for 1. Theoretical calculations using density functional (DFT) and ab initio Hartree-Fock theory have been carried out for 1 and 3a,b. The results are consistent with the experimental data. Conclusions on the behavior of a thioamide, when used as an antithyroid drug, have also been made.

Direct reaction of 6‐n‐propyl‐2‐thiouracil (PTU), a widely used anti‐thyroid drug against hyperthyroidism (Graves’ disease), or 5‐chloro‐2‐mercaptobenzothiazole (CMBZTH) with iodine in a molar ratio of 1:1 resulted in the formation of the charge‐transfer (CT) complexes [(PTU)I2] (1) or [(CMBZT)I2] (2). All reactions were carried out in dichloromethane and water solutions. Compounds 1 and 2 were characterized by elemental analyses, FT‐Raman, FT‐IR, UV/Vis and 1H NMR spectroscopy. The crystal structures of both complexes were determined by X‐ray diffraction at 120(1) K (1) and 293(2) K (2). The charge‐transfer nature of the bonds in the adducts 1 and 2 was verified by the lengthening of the I−I bond lengths as compared to the S−I bond lengths and by the characteristic CT bands observed in the UV spectra of the complexes. Compound 1 [(C7H10N2OS)I2] [monoclinic with space group P21/c and a = 9.8501(7), b = 10.3101(7), c = 12.0287(8) Å, β = 99.707(6)°, Z = 4] consists of a propylthiouracil ligand bonded with an iodine atom through sulfur. Extended intermolecular N−H···O contacts link the molecules forming a supramolecular assembly. Compound 2 {(C7H4ClNS2)I2} [orthorhombic, space group P212121, a = 4.1650(10), b = 9.691(2), c = 28.471(6) Å, Z = 4] consists of a 5‐chloro‐2‐mercaptobenzothiazole ligand bonded with an iodine atom through sulfur. An extended intermolecular linkage via I···H−N bonds leads to the formation of an extended structure. Attempts to draw conclusions on the behavior of a thioamide — when used as an anti‐thyroidal drug — towards iodine have been made. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

The reaction of 2-pyrimidone hydrochloride ([C(4)H(5)N(2)O](+)[Cl](-) or [PMOH(2)](+)[Cl](-)) with diiodine in a dichloromethane-methanol solution resulted in the formation of ([C(4)H(5)N(2)O](+))(2)[I(2)Cl(2)](2-) (1) complex. The compound was characterized by elemental analysis, FT-IR, DTA-TG and conductivity titrations. The crystal structure of 1 was also determined by X-ray diffraction at 294(1) K. Compound 1 is monoclinic, space group P2(1)/n, consisting of two cationic [PMOH(2)](+) species and a [I(2)Cl(2)](2-) counter dianion. The cation is in its keto form. Direct reaction of thiazolidine-2-thione (tzdtH), with diiodine in dichloromethane solution, on the other hand, led to the formation of a crystalline solid which contained two complexes of formulae [(tzdtH)(2)I](+)[I(3)](-).2I(2) (2) and [(tzdtH)I(2)](2).I(2) (2a) in a ratio of 90 to 10%. Complex 2a was characterized by X-ray analysis at 180(2) K. Compound is monoclinic, space group C2/c and contains two units of [(tzdtH)I(2)] "spoke" structures. Compound 1, as well as the known species iodonium salt [(tzdtH)(2)I](+)[I(3)](-).2I(2) (2) and the charge transfer (CT) iodine complexes of formulae [(bztzdtH)I(2)] (3) and [(bztzdtH)I(2)].I(2) (4) (bztzdtH = 2-mercaptobenzothiazole) with "spoke" and extended "spoke" structures respectively, were tested for their oxidizing activity towards 3,5-di-tert-butylcatechol to 3,5-di-tert-butyl-o-benzoquinone.