Direct reaction of thiazolidine-2-thione (tzdtH), an anti-thyroidal agent with diiodine in a molar ratio of 1:2 caused the heterolytic cleavage of diiodine and formation of [{(tzdtH)(2)I+}.I-3(-).2I(2)] (1), whereas the reaction of benzothidzole-2-thione (bztzdtH) with diiodine in a molar ratio of 1:2 and 1:1 resulted in the formation of the [{(bztzdtH)I-2}.I-2} (2) and [(bztzdtH)I-2] (3) charge-transfer (c.t,) complexes, In addition, the reaction between benzimidazole-2-thione (bzimtH) with diiodine in a molar ratio 1:2 yielded the c.t. complex [{(bzimtH)I-2}(2).I-2.2H(2)O] (4), All reactions were carried out in dichloromethane. The molecules have been characterized by m.p., elemental analyses, and FT-Raman, FT-IR, UV/Vis and H-1 NMR spectroscopy. Crystal structures of the named complexes have been determined by X-ray diffraction at -103 degreesC (1), 20 degreesC (2 and 3) and -168 degreesC (4), The charge-transfer nature of the bonds of the adducts (1-4) has been verified by the lengthening of the I-I bond lengths as compared to the S-I bond lengths, by the characteristic c.t. bands observed in the UV spectra and by the shifts of frequencies measured for the I-I bond vibration in the FT-Rdman spectra of the complexes, Compound 1 (C3H5NS2I4) is monoclinic with a space group P2(1)/n and a = 9.145(2) Angstrom, b = 13.259(2) Angstrom, c = 10.615(2) Angstrom, beta = 106.30(2)degrees, Z = 4. The complex is ionic, containing an S-I+-S linkage and an I-3(-) Compound 2 3 counter anion. {C7H5NS2I4, monoclinic, space group P2(1)/n, a = 8.357(2) Angstrom, b = 17.829(4) Angstrom, c = 9.603(2) Angstrom, Z = 4, beta = 94.39(3)degrees] consists of a benzothiazole-2-thione ligand bonded with an iodine atom through a sulfur atom. A neutral diiodine molecule is also cocrystallized. A benzothiazole-2-thione ligand is also bonded through its sulfur atom to an iodine atom in molecule 3 [C7H5NS2I2, orthorhombic, space group P2(1)2(1)2(1), a = 4.189(1) Angstrom, b = 9.770(3) Angstrom, c = 27.704(8) Angstrom, Z = 4]. Extended intramolecular N-H...I contacts link the molecules forming a supramolecular assembly, The crystal structure of 4 (C7H6N2SI3.H2O) reveals a monoclinic space group P2(1)/c and a = 13.4828(14) Angstrom, b = 4.6704(4) Angstrom, c = 21.267(2) Angstrom, beta = 101.029(8)degrees, Z = 4. It consists of a benzimidazole-2-thione ligand bonded to an iodine atom through a sulfur atom. An extended intramolecular linkage via I(2)...H(4)[C(4)] leads to the formation of dimers, while an extended hydrogen-bonding network {H(12w)[O(12)w]...N (3), O(1w)...N(3)} links the alternate parallel dimers forming a supramolecular assembly. Attempts to draw conclusions on the behavior of a thione, when used as an anti-thyroidal agent, towards diiodine have been made. (C) Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002.
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