Charge-transfer complexes of Benzoxazole-2(3H)-thione and Benzoxazole-2(3H)-selone with diiodine: X-ray crystal structure of Benzoxazole-2(3H)-thionebis(diiodine)

Solids of stoichiometry 1 . I-2 (C7H5I2NOS; I), 1 . 2I(2) (C7H5I4NOS; II), 2 . I-2 (C7H5I2NOSe; III) and 2 . 2I(2) (C7H5I4NOSe; IV) have been obtained by reacting respectively benzoxazole-2(3H)-thione (1) and benzoxazole-2(3H)-selone (2) with molecular diiodine in a 1:1 or 1:2 molar ratio in CH2Cl2 solution. Crystals suitable for X-ray structure determination have been obtained only for II and contain units formed by one diiodine molecule bonded almost linearly [178.44(4)degrees] to the thionic sulphur atom of 1 and another diiodine molecule weakly interacting with the former. The FT-Raman spectrum in the characteristic nu(I-I) region shows two bands for compound II at 176 and 159 cm(-1), in accordance with the presence of two differently perturbed diiodine molecules [I(1)-I(2) = 2.769(1) Angstrom, I(3)-I(4) = 2.729(1)Angstrom]. The FT-IR and FT-Raman spectra of compounds I, III and IV are discussed in comparison with the spectrum of II and with those reported for similar charge transfer complexes.