Hydrothermal. scandium fluoride chemistry: syntheses and crystal structures of [C2N2H10][ScF5], [NH4](2)[Sc3F11] and [H3O][C6N2H16][ScF6]center dot H2O

The hydrothermal syntheses and crystal structures of three new scandium fluorides are reported. [enH(2)][ScF5] 1 exhibits continuous chains of vertex linked ScF6 octahedra, which adopt two differing conformations (eclipsed and staggered). [NH4](2)[Sc3F11]2, displays a three-dimensional framework structure composed of edge and corner-shared ScF7 pentagonal bipyramids interlinked via octahedral scandium centres. This structure encloses 'butterfly'-shaped channels, and may be regarded as an 'expanded' version of the KSc2F7 structure, derived by insertion of the additional octahedral unit between neighbouring pentagonal bipyramidal chains. [H3O][C6N2H16][ScF6]-H2O 3 is composed of isolated ScF6 octahedra hydrogen-bonded to trans-1,4-diaminocyclohexane cations and water molecules/hydronium cations. Crystal data for 1: tetragonal, space group P4/ncc, a = 13.035(2) angstrom, c = 8.142(2) angstrom; for 2: orthorhombic, space group Cmmm, a = 18.501(12) angstrom, b = 6.613(5) angstrom, c = 4.025(3) angstrom; for 3: monoclinic, space group P2(1)/n, a = 9.543(2) angstrom, b = 6.704(1) angstrom, c = 9.873(2)angstrom, beta = 90.349(5)degrees. (c) 2005 Elsevier SAS. All rights reserved.