Syntheses Raman spectroscopy and crystal structures of alkali hexa­fluorido­rhenates(IV) revisited

摘要

The A 2[ReF6] (A = K, Rb and Cs) salts are isotypic and crystallize in the trigonal space group type P m1, adopting the K2[GeF6] structure type. Common to all A 2[ReF6] structures are slightly distorted octa­hedral [ReF6]²⁻ anions with an average Re—F bond length of 1.951 (8) Å. In those salts, symmetry lowering on the local [ReF6]²⁻ anions from Oh (free anion) to D 3d (solid-state structure) occur. The distortions of the [ReF6]²⁻ anions, as observed in their Raman spectra, are correlated to the size of the counter-cations.