CRYSTAL STRUCTURE OF GALLIUM AND CHROMIUM SALTS BELONGING TO THE FAMILY M^IIIH₂P₃O₁₀·2H₂O (FORM I)

Abstract

The crystal structures of two acid triphosphates, GaH₂P₃O₁₀·2H₂O and CrH₂P₃O₁₀·2H₂O of form I, have been obtained from Rietveld refinement using X-ray powder diffraction data. The compounds crystallize in the monoclinic space group P2/c, with unit cell dimensions a = 7.9663(10), b = 4.9669(5), c = 11.7586(13) Å, β = 95.199(6)° for GaH₂P₃O₁₀·2H₂O, and a = 7.9603(14), b = 4.9963(7), c = 11.7877(17) Å, β = 95.068(9)° for CrH₂P₃O₁₀·2H₂O; Z = 2. The compounds have a layered crystal structure, with metal-triphosphate 2D polymeric network, parallel to the bc plane, and water molecules lying in interlayer space. Comparison with related structures is given.