STRUCTURES OF DIMETHYLAMMONIUM METAL(III) SULFATE HEXAHYDRATES (METAL=AL,CR)

(I) [Al(H2O)6]3+.C2H8N+.2SO42-, M(r) = 373.28, monoclinic, P2(1)/n, a = 6.408 (1), b = 10.752 (1), c = 11.134 (2) angstrom, beta = 100.44 (1)-degrees, V = 754.4 (2) angstrom 3, Z = 2, D(x) = 1.643, D(m) = 1.62 g cm-3, lambda(Mo K-alpha) = 0.71073 angstrom, mu = 4.7 cm-1, F(000) = 392, T = 295 K, R = 0.040 for 1680 reflections with I > 4-sigma(I). (II) [Cr(H2O)6]3+.C2H8N+.2SO42-, M(r) = 398.29, monoclinic, P2(1)/n, a = 6.391 (8), b = 10.748 (3), c = 11.40 (1) angstrom, beta = 100.87 (6)-degrees, V = 769 (1) angstrom 3, Z = 2, D(x) = 1.720, D(m) = 1.64 g cm-3, lambda(Mo K-alpha) = 0.71073 angstrom, mu = 10.5 cm-1, F(000) = 414, T = 295 K, R = 0.038 for 1666 reflections with I > 4-sigma(I). The Al and Cr atoms are octahedrally coordinated by the water molecules showing Al-Ow and Cr-Ow bond lengths ranging from 1.874 (2) to 1.891 (2) angstrom and from 1.953 (2) to 1.967 (2) angstrom, respectively. The dimethylammonium cations are disordered, with each NH2 group having two centrosymmetric positions. The hydrogen bonds between O atoms of a sulfate anion acting as acceptors, water molecules and a dimethylammonium cation acting as a donor range from 2.586 (3) to 2.87 (1) angstrom.