Hydrothermal scandium fluoride chemistry: syntheses and crystal structures of [C2N2H10][ScF5], [NH4]2[Sc3F11] and [H3O][C6N2H16][ScF6]⋅H2O

The hydrothermal syntheses and crystal structures of three new scandium fluorides are reported. [enH2][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) Åa=13.035(2) Å, c=8.142(2) Åc=8.142(2) Å; for 2: orthorhombic, space group Cmmm, a=18.501(12) Åa=18.501(12) Å, b=6.613(5) Åb=6.613(5) Å, c=4.025(3) Åc=4.025(3) Å; for 3: monoclinic, space group P21/n, a=9.543(2) Åa=9.543(2) Å, b=6.704(1) Åb=6.704(1) Å, c=9.873(2) Åc=9.873(2) Å, β=90.349(5)°β=90.349(5)°.

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