HALOCUPRATES(II) OF TRIAMTERINIUM, A DIPROTONATED PTERIDINE DERIVATIVE - CRYSTAL-STRUCTURE OF (TRIAMTERINIUM)CUCL4 - ELECTRONIC AND EPR CHARACTERIZATION OF (TRIAMTERINIUM)CUX4 (X = CL, BR)

The crystal structure of triamterinium tetrachlorocuprate(II), (C12H13 N7)CuCl4, was determined by X-ray diffraction. The crystals are monocl inic, P2(1)/n, with a = 13.959(3), b = 7.118(2), c = 17.280(5) angstro m, beta = 99.99(2)-degrees, V = 1690.9(9) angstrom3 and Z = 4. A final R value of 0.031 was obtained. The structure consists of the [CuCl4]2 - anion and a triamterinium diprotonated cation. The [CuCl4]2- anion s hows a flattened tetrahedral geometry, the two larger Cl-Cu-Cl angles being 133.83 and 143.71-degrees; the dihedral angle is 31.13'. The Cu- Cl distances range from 2.23 to 2.29 angstrom. The spectroscopic and m agnetic results of [CUCl4]2- and [CuBr4]2- are in agreement with a hig h distortion of these ions from the tetrahedral configuration. Accordi ng to the sites of protonation of the triamterene, the best donor atom s are the endocyclic N(3) and N(8) atoms.