K 2AlF 5 · H 2O: Location of hydrogen atoms by X-ray diffraction and Raman spectroscopy study

Abstract

The complete structural determination of K 2AlF 5 · H 2O is achieved by X-ray diffraction on a single crystal. As previously described, the cell is orthorhombic ( Cmcm, a = 9.200(3), b = 8.119(4), c = 7.486(3) Å, Z = 4). The structure is essentially characterized by very slightly kinked chains of AlF 6 octahedra, sharing opposite corners, running in the [001] direction. Hydrogen atoms are located by difference Fourier synthesis on 8f positions; their introduction in the structural model improved the final results significantly ( R = 0.0383, R w = 0.0283). The OH … F hydrogen bonding system is discussed with the help of Raman spectroscopy.