Synthesis and structure of decaaqua-hexasodium-calcium bis-nitrilotris(methylenephosphonate) bis(hexaaquasodium) tetrahydrate [CaNa6{NH(CH2PO3)3}2(H2O)10][Na(H2O)6]2 · 4H2O

The product of the reaction of tetrasodium nitrilotris(methylenephosphonate) Na4H(NH(CH2PO3)3) with Ca(OH)2 having the formula [CaNa6{NH(CH2PO3)3}2(H2O)10][Na(H2O)6]2 · 4H2O (sp. gr. P21/c, Z = 2, a = 12.0579(4) Å, b = 10.4569(3) Å, c = 19.9346(4) Å, β = 95.355(2)°) was synthesized and characterized. The complex anion consists of a ring composed of six hydrate-bridged Na atoms. The cavity of the anion incorporates a Ca atom coordinated by two phosphonate ligands in a distorted octahedral geometry. Each of the two complex cations contains a sodium ion octahedrally coordinated by six water molecules. The crystal packing consists of infinite ribbons of the complex anions, which are linked by hydrate bridges to form layers alternating with layers of the complex cations and interlayers composed of disordered water molecules of solvation.