The crystal structure of Cd(DATP)Cl 2·H 2O has been determined by X-ray diffraction methods. It crystallizes in the tetragonal space group I4 1 cd with a = 24.296(7), c = 7.108(9) Å, V = 4196(4) Å 3, and Z = 16. The structure has been solved by Patterson and Fourier syntheses and refined by full-matrix least-squares procedure to R = 0.049 for 1688 observed reflections. The crystal does not contain individual Cd(DATP)Cl 2·H 2O neutral molecules. Cadmium atoms show a coordination number of six. On the basis of the molecular structure of the Cd(DATP)Cl 2·H 2O complex the most significant IR bands have been assigned in the 4000-600 cm −1 range. Likewise, the v(CdN), v(CdS) and v(CdX) bands were assigned by comparing the IR spectra of the Cd(DATP)Cl 2·H 2O and Cd(DATP) 2Br 2 complexes in the 600–180 cm −1 range. Finally, by using an IR technique for the identification of intermediates, a thermal decomposition mechanism for the Cd(DATP)Cl 2·H 2O complex has been proposed.