Reactions of KBrF₄ with platinum metals

The reaction of various platinum metals (M = Ru, Os, Rh, Ir, Pd, Pt) with KBrF₄ was investigated upon heating their mixtures to 400 °C. The formation of potassium fluorido platinum metallates in oxidation states +4 or +5, K₂MF₆ or KMF₆, respectively, was observed in all cases. The obtained products were tested for their stability in water. Depending on the platinum metal, they were either stable, were reduced to the oxidation state +4, or were hydrolyzed to so far unidentified phases. K₂RuF₆, K₂OsF₆, α-K₂PdF₆, β-K₂PdF₆, which were previously only poorly characterized, were structurally reinvestigated by single crystal or powder X-ray diffraction, Raman and IR spectroscopy. The three former compounds crystallize isotypic in the trigonal, the latter in the hexagonal crystal system. The α→β phase transition of K₂PdF₆ was found to be reconstructive. Quantum chemical calculations were used to investigate the crystal structures.