[Cu₂(HF₂)(H₂O)₈][AlF₆]·2H₂O

Abstract

The title compound, octaaqua-(hydrogendifluorido)-di-cop-per(II) hexa-fluoridoaluminate dihydrate, was obtained under hydro-thermal conditions. The structure is isotypic with that of the analogous Fe(III) compound, [Cu(2)(HF(2))(H(2)O)(8)][FeF(6)]·2H(2)O. The coordination sphere of the Cu(II) atom is formed by one F and three water O atoms at short distances < 2 Å and is augmented by two additional water O atoms at significantly longer distances, leading to a considerably distorted octa-hedral environment. By edge-sharing, these octa-hedra form dimeric [Cu(2)(HF(2))(H(2)O)(8)](3+) units that are bonded to [AlF(6)](3-) anions ( symmetry) and to crystal lattice water mol-ecules via hydrogen bonds. Besides F-H⋯F inter-actions between the dimeric cationic units, O-H⋯F and O-H⋯O hydrogen bonds (both in part bifurcated) are observed.