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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)

FT-Infrared and FT-Raman spectra are presented for a series of Mes*NP derivatives. 15N−labeled samples and comparisons between compounds allow for reliable assignment of NP stretching frequencies. The observed isotopic shift is consistent with calculated values, and assignments are supported by the observation of a relationship between the relative Raman intensity of the NP stretch and the bond angle at the nitrogen center (C−N−P).

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