THE SOLID-STATE CHEMISTRY AND POLYMORPHISM OF AQUOMAGNESIUM HYDROGEN PHTHALATES

Five crystalline phases of magnesium hydrogen phthalate are described. The structures contain two, six or eight molecules of water per cation. Full crystal structures of two of the series (di-aquomagnesium hydrogen phthalate and hexa-aquomagnesium hydrogen phthalate) are reported and some general features of all the hydrogen phthalates are discussed. Di-aquomagnesium hydrogen phthalate: Mg2+.2C8O4H5−. 2H2O, Mr = 390.60, monoclinic, P21/c, a = 12.916(1), b = 5.092(1), c = 12.956(2) Å, β = 113.98(1)°, V = 778 Å3, Z = 2, Dx = 1.66 g cm−3, λ,(Mo Kα) = 0.71069 Å, μ = 1.24 cm−1, F(000) = 400, T = 295 K, R = 0.058 for 967 observed reflections. Hexa-aquomagnesium hydrogen phthalate: Mg2+.(C8O4H5−)2.6H2O Mr = 462.65, monoclinic, C2/m, a = 16.674(3), b = 9.811(2), c =6.288(2) Å, b = 98.20(2)°, V = 1 018.0 Å3, Z = 2, Dx = 1.50 g cm−3, λ(Mo Kα) = 0.71069 Å, μ = 1.13 cm−1, F(000) = 480.0, T = 295 K, R = 0.033 for 681 observed reflections. © 1992, Taylor & Francis Group, LLC. All rights reserved.