Pd(SeO3), Pd(SeO4), and Pd(Se2O5): The First Palladium Oxoselenates

Abstract

AbstractDepending on the reaction conditions, the reaction of elemental palladium with H2SeO4 in sealed glass tubes at 350 °C leads to red single crystals of Pd(SeO3) [C2/m, Z = 4, a = 6.788(2), b = 7.030(2), c = 7.008(2) Å, β = 118.09(3)°] or to yellow‐orange single crystals of Pd(SeO4) [C2/c, Z = 4, a = 8.171(1), b = 5.286(1), c = 8.115(1) Å, β = 94.54(1)°]. Yellow‐orange single crystals of Pd(Se2O5) [I2/a, Z = 4, a = 7.212(1), b = 5.569(1), c = 12.177(3) Å, β = 106.84(2)°] are obtained when SeO3 is added to the reaction mixture. X‐ray single‐crystal diffraction shows that Pd(SeO3) consists of layers that are formed by square‐planar coordinated Pd2+ ions and pyramidal SeO32– groups. These layers are held together by weak interactions involving the lone electron pairs of the selenium atoms. The Se–O distances within the selenite ion are different (1.69 and 1.76 Å), in accordance with the different attachment of the oxygen atoms to the Pd2+ ions. The square‐planar [PdO4] units in the crystal structure of Pd(SeO4) are linked by tetrahedral SeO42– ions into a three‐dimensional network. These anions act as monodentate ligands towards the Pd2+ ions, with Se–O distances of around 1.65 Å. The Pd2+ ions in the crystal structure of Pd(Se2O5) are coordinated by two chelating diselenite ions. The Se2O52– ions link the palladium ions into corrugated chains, which are held together by weak interactions only. The IR spectra of these compounds display the typical bands for oxoselenate anions.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)