Sur L'Existence d'un Intermediaire Reactionnel Entre Phosphate et Pyrophosphate Acide de Potassium: Cas de K 2 H 8 (PO 4 ) 2 P 2 O 7

On the Existence of Intermediate Reaction Products of Potassium Hydrogen Phosphate and Diphosphate: K 2 H 8 (PO 4 ) 2 P 2 O 7 The crystal structure of K 2 H 8 (PO 4 ) 2 P 2 O 7 has been determined from diffractometer data obtained using MoKα radiation. The space group is Pca2 1 with a = 9.364(2), b = 7.458(2) and c = 19.560(2) Å, V = 1 366.0 Å 3 ; d m = 2.17(1) g/cm 3 . Z = 4 · μ(MoKα) = 12.47 cm −1 . The structure was solved by direct methods. The crystal structure was refined to R = 0.025 for 416 independent reflexions. Two kinds of PO 4 exist and the mean value of PO is 1.55(2) Å for one and 1.53(2) Å for the other. In P 2 O 7 the angle POP is 135(1)°. The distances PO of bridge are 1.59(2) and 1.57(2) Å the mean value of PO in terminals PO 3 is 1.51(2) Å. The coordination numbers of the potassium ions are nine and eight. K 2 H 8 (PO 4 ) 2 P 2 O 7 , compound with mixed anion PO 4 /P 2 O 7 may be considered as reactional intermediary between acid orthophosphate and pyrophosphate.