Structure of copper(II) perchlorate hexahydrate.

Cu(ClO4)2.6H2O, Mr = 370.54, monoclinic, P2(1)/c, a = 5.137 (1), b = 22.991 (3), c = 13.849 (2) A, beta = 90.66 (1) degree, V = 1635.4 (4) A3, Z = 6, Dx = 2.26 g cm-3, lambda(Mo K alpha) = 0.71069 A, mu = 26.44 cm-1, T = 296 K, F(000) = 1122, 2911 unique reflections having I greater than sigma 1, R = 0.030. Each of the two inequivalent copper ions is coordinated by six water-molecule O atoms in a significantly distorted octahedral arrangement. Each of the three inequivalent but geometrically quite similar perchlorate groups is slightly distorted from regular tetrahedral geometry. The overall observed mean Cl-O distance is 1.429 (5) A while the overall observed mean perchlorate O-O distance is 2.333 (8) A. Both the Cu-O complexes and the perchlorate ions were tested and found to behave as rigid bodies. The perchlorate-ion parameters corrected for rigid-body motion are: overall mean Cl-O distance, 1.453 (6) A; overall mean perchlorate O-O distance, 2.372 (8) A. Location and refinement of the 18 H atoms gave a detailed account of hydrogen bonding, which occurs between oxygen octahedra, between oxygen octahedra and perchlorate groups, and, more weakly, within oxygen octahedra.