Conductivity, FT-Raman and X-ray crystal structures of two novel [D2I]In ( n= 3 and D = N-methylbenzothiazole-2-selone ; n= 7 and D = N-methylbenzothiazole-2-thione)iodonium salts. First example of I-•3I2 heptaiodide

Solids of stoichiometry 1.2I2 (C8H7I4NS2; I) and 2.I2 (C8H7I2NSSe; II) are obtained respectively from mixtures of N-methylbenzothiazole-2(3H)-thione (1) and N-methylbenzothiazole-2(3H)-selone (2) with molecular diiodine in CH2Cl2 when the solutions were allowed to stand. The crystals of I are monoclinic (a = 9.445(1) angstrom, b = 18.233(2) angstrom, c = 18.673(2) angstrom, beta = 98.62(1)-degrees, Z = 4, space group P2(1)/c; R = 0.030) and consist of the [(1)2I]+ cations and I7- anions, formed by interaction of I- with three diiodine molecules (short distances ranging between 2.746 and 2.771 angstrom, long distances between 3.237 and 3.260 angstrom). The I7- anions interact weakly with each other (3.502 angstrom) to form parallel chains of anions; the cations are located between these chains. The crystals of II are triclinic (a = 12.147(10) angstrom, b = 9.681(4) angstrom, c = 10.950(4) angstrom, alpha = 71.03(2)-degrees, beta = 93.93(2)-degrees, gamma = 99.14(2)-degrees, Z = 1, space group P1BAR; R =0.027) and consist of [(2)2I]+ cations and triiodide anions located on different crystallographic centers (d(I-I) = 2.899 and 2.919 angstrom for the two differently positioned triiodides). The FT-Raman spectra in the characteristic v(I-I) region show a very strong band for compound II at 121.2 cm-1, in accordance with the presence of a symmetrical triiodide anion, while for I the medium peak at 175.2 cm-1 and the strong one at 157.4 cm-1 are indicative of the presence of perturbed diiodine molecules, as generally found in donor-12 adducts of weak or medium-weak strength. Both compounds have very low electric conductivity