The title compounds were prepared by mixing either aqueous and / or
ethanolic solutions of YCl3.6H2O and violuric acid monohydrate in mole ratio
(1:2). The prepared crystalline complex belongs to orthorhombic system, with
unit cell constants: a = 8.6925(4), b = 17.0421(9), c = 5.5285(3) Å, V =
818.98(7) Å3, Z = 2, space group P21 21 2 (half the molecule occupies the
asymmetric unit cell). The structure was solved by direct method using SIR 92
software and then refined by full matrix least square using anisotropic
temperature factors. The hydrogen atoms were located and their positions and
isotropic temperature factors were refined giving R-factor 0.061 and wR 0.134.
The thermogravimetric analyses for the prepared complexes were studied under
nitrogen gas and the activation energies of decomposition steps were
determined.