The oxidation of elemental palladium with oleum (65 % SO3) in the presence of barium carbonate in torch-sealed glass ampoules at 180 °C leads to yellow single crystals of the heteroleptic palladate Ba2[Pd(HS2O7)2(S3O10)2] (triclinic, P1; Z=1; a=884.18(3), b=927.68(3), c=938.77(4) pm; α=60.473(1), β=80.266(2), γ=87.746(2)°). The crystal structure shows the Pd(2+) ions in a square-planar coordination of oxygen atoms of two hydrogendisulfate as well as of two trisulfate anions. The compound is the first example of the rarely seen S3O10(2-) and HS2O7(-) anions acting as ligands in a complex anion and, moreover, the first heteroleptic polysulfatometallate known so far. The complex formation leads to a stabilization of the trisulfate anion relative to its uncoordinated congener. Ba2[Pd(HS2O7)2(S3O10)2] has been further characterized by vibrational spectroscopy and quantum chemical calculations. Thermal analyses by means of thermogravimetric/differential thermal analysis (TG/DTA) measurements show that the compound decomposes to yield elemental palladium and BaSO4.
Keywords: palladium; quantum chemistry; sulfates; thermal analysis; vibrational spectroscopy.
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