Preparation and crystal structure of potassium cyclodecaphosphate tetrahydrate: K10P10O30 · 4H2O

Chemical preparation and crystal structure of K₁₀P₁₀O₃₀ · 4H₂O are described. This compound, the second example of a cyclophosphate with a twenty membered ring, is monoclinic C2/c, with Z = 4, and the following unit-cell dimensions: a = 15.342(5), b = 11.846(5), c = 19.264(5) Å, β = 91.27(3)·. The crystal structure was solved by using 4379 unique reflections the final R value being 0.034. The P₁₀O₃₀ ring anions spread in layers approximately parallel to the (101) planes. These layers are interconnected by the various KO₈ and KO₇ polyhedra and by the hydrogen bonds. The P₁₀O₃₀ ring anion has a twofold internal symmetry induced by a twofold axis passing through two opposite bonding oxygen atoms of the ring.