Etude des Propriétés Physico-Chimiques de CuK 4 (P 3 O 9 ) 2 .4H 2 O

The dehydration of CuK 4 (P 3 O 9 ) 2 .4H 2 O was investigated, between 25 and 700°;C, by TG-DTA, x-ray diffraction, and IR. It leads, at 500°;C, to a mixture of long chain polyphosphates KPO 3 and CuK 2 (PO 3 ) 4 which remains stable until its melting point. The kinetic characteristics of the dehydration of CuK 4 (P 3 O 9 ) 2 .4H 2 O were determined and discussed. The vibrational spectrum of the title compound, CuK 4 (P 3 O 9 ) 2 .4H 2 O, was interpreted in the domain of the stretching vibrations of the P 3 O 9 rings on the basis of its crystalline structure and in the light of the calculation of the normal IR frequencies of the P 3 O 9 ring with the idealized D 3h symmetry.