The cyclohexaphosphoric acid is added until pH 2 is Three new cyclohexaphosphates with the general formula reached in the final solution. After some days of slow Ca 2 M 2 P 6 O 18 ؒ 6H 2 O (M ؍ K, Tl, Rb) are reported. They crystal-evaporation at room temperature, crystals appeared with lize with monoclinic unit cells and are isotopic. As an example a suitable dimension. They were sparingly soluble in water the paramters of Ca 2 K 2 P 6 O 18 ؒ 6H 2 O are a ؍ 7.266(1), b ؍ and stable in air for months under normal conditions of 11.833(2), c ؍ 12.300(2) A ˚,  ؍ 103.17(1)؇, Z ؍ 2, P2 1 /n, V ؍ temperature and hygrometry.
1030(3) A ˚3, and Dx ؍ 2.387 g cm ؊3 . Crystal structure of this
The cyclohexaphosphoric acid used in this reaction was phase was determined using 6292 independent reflections with prepared from an aqueous solution of Li 6 P 6 O 18 и 6H 2 O (2) a final R ؍ 0.025. The atomic arrangement can be described passed through an ion-exchange resin (Amberlite IR 120).
as puckered layers containing water bonded P 6 O 18 anions and The compounds have been studied using different tech-Ca 2؉ and K ؉ cations, alternating along the (1, 0, 1) direction. niques with the experimental conditions described below.
Synthesis and characterization by X-ray diffraction, IR absorption, and TA are described.