Crystal structure of pyridinium periodate

The crystal structure of the room-temperature ferroelectric phase of pyridi nium periodate [C6H5NH](+)[IO4](-) has been determined by X-ray diffraction as orthorhombic, space group Cmc2(1) with a = 8.347(2), b = 7.270(2), c = 12.732(3) Angstrom and Z = 4. It was refined to R1 = 0.0281 wR2 = 0.0762 fo r 389 absorption-corrected reflections. The structure comprises isolated IO 4 tetrahedra linked together by disordered pyridinium cations involved in a network of bifurcated hydrogen bonds. The average I-O distance is found to be 1.75(1) Angstrom.