Interaction in the potassium tetrametaphosphimate-praseodymium chloride-water system

The interaction between tetrametaphosphinic acid anion, TtMPm4-, with Pr3+ cation in the K4TtMPm-PrCl3-H2O system in the range of initial K4TtMPm:PrCl3(n) ratios between 0.25 and 10 at a starting PrCl3 concentration of 0.05 M has been investigated. Three phases differing in TtMPm4:Pr3+(nsup(T)) ratio have been found to exist in the initial K4TtMPm:PrCl3 ratio range studied. A poorly soluble Pr4(TtMPm)3x36H2O phase described by an nsup(T) value of 0.75 exists in equilibrium with the solution in the ratio range of n(<=)0.75. In the range 1(<=)n(<=)1.5 an essentially insoluble phase KPrTtMPmx9H2O is formed. At n=2.2 (and further up to n=10), a crystallic phase, K4HPr(TtMPm)2x19H2O, is revealed to be formed. The IR spectra of the compounds obtained have been taken