Crystal structure and phase transition of the quinolinium tetrabromothallate(III)
Résumé
The salt quinolinium tetrabromothallate(III) is orthorhombic Pna2(1) with the following unit cell dimensions: a = 9.582(2), b = 10.0210(19), c = 14.916(2) angstrom, Z = 4. The structure was solved by Patterson methods and refined to a final R-value of 0.0452 for 2043 observed reflections. The examination of the structure shows quinolinium cations separating chains of tetrahedral TlBr4-, these chains are perpendicular to the c axis. Infrared spectra confirms the presence of the organic cations, differential scanning calorimetry reveals a transition at T = 406 K. Electrical measurements and X-ray powder diffraction were performed to discuss the mechanism of the phase transition.