Crystal Structure of Tetra- and Pentasodium Salts of Nitrilotris(methylenephosphonic Acid)

Abstract

Tetra- and pentasodium salts of nitrilotris(methylenephosphonic acid) N(CH₂PO₃)₃H₆ (NTP) have been studied by single-crystal X-ray diffraction and spectroscopy. [Na₈(H₂O)₁₂{NH(CH₂PO₃)₃H}₂] · H₂O crystallizes in triclinic system, space group P1̅, Z = 1, a = 7.1515(2) Å, b = 11.1590(3) Å, c = 12.0583(3) Å; α = 92.077(2)°, β = 106.145(2)°, γ = 5.628(2)°, CCDC No. 1432091. The crystal structure comprises two-dimensional layers lying along planes (011̅), where dimeric molecules are linked by bridges each comprising four Na hydration octahedra. The [Na₅(H₂O)₁₁{NH(CH₂PO₃)₃}] · 2H₂O crystals are monoclinic, space group P2₁/n, Z = 4, a = 6.3024(2) Å, b = 21.5639(7) Å, c = 18.1608(6) Å; β = 91.261(3)°, CCDC No. 1497161. The crystal packing comprises alternating layers in planes [020] made of two-dimensional nets of Na hydration polyhedra, and columns of Na hydration octahedra lying in planes [040], with acid moieties in between.