AL3-CENTER-DOT-H2O] SINGLE-CRYSTALS( ION SITE SYMMETRY IN (NH4)(2)[ALF5)

The production of pure and Cr3+ doped (NH4)(2)[AlF5.H2O] single crysta ls and the crystal structure of this compound are described. The infra red spectra recorded experimentally at room temperature show - using t he results of group theory - that the [AlF5.H2O](2-) complex ion has a t most the symmetry of the C-4v group. EPR measurements are carried ou t for a more exact determination of the site symmetry of Al3+ ions usi ng the Cr3+ ion on Al3+ site as ''probe ion''. The determined values o f spin-Hamiltonian parameters suggest that the symmetry of the [AlF5.H 2O](2-) complex ion has at most the symmetry of the C-2v group.