PREPARATION OF 1,3,2,4,6-DITHIATRIAZINES WITH SUBSTITUTED ARYL GROUPS AND THE X-RAY CRYSTAL-STRUCTURE OF THE (4-CHLOROPHENYL)DITHIATRIAZINE DIMER

The synthesis of XC6H4CN5S3, XC6H4CN3S2Cl2, {XC6H4CN3S2}2, and XC6H4CN3S2.C7H10 (X = 4-CH3, 4-Cl, 3-CF3, 4-CF3, 4-CH3O, 4-C6H5) is reported. The crystal structure of {4-ClC6H4CN3S2}2 was determined by a single-crystal X-ray diffraction study. The compound crystallizes in the triclinic space group P1BAR with Z = 2 in a cell of dimensions a = 6.107 (1) angstrom, b = 12.070 (2) angstrom, c = 13.206 angstrom, alpha = 113.73 (1)-degrees, beta = 99.04 (2)-degrees, and gamma = 97.53 (2)-degrees. The least-squares refinement with anisotropic thermal parameters for all non-hydrogen atoms converged at R = 0.084 for 1480 unique reflections. The structure is a cofacial dimer of 4-ClC6H4CN3S2 units, with short S...S contacts of 2.509 (4) and 2.534 (4) angstrom. Dimer units are stacked head-to-tail in the crystal along the bc diagonal. H-1-NMR studies of the more soluble compounds show significant shielding of the aromatic protons (0.3-0.6 ppm) attributable to ring currents of adjacent aromatic rings. This is consistent with the preservation in solution of the wedge-shaped dimeric structure found in the solid state.