Phase relationships in the uranium-palladium-sulfur system: I. Characterization and crystal structure of UPd2S4

The new compound UPd₂S₄ was prepared by reacting stoichiometric amounts of US₂, Pd, and S in evacuated quartz ampoules. UPd₂S₄ crystallizes in the tetragonal system, a = b = 6.734(1), c = 11.841(4)Å, space group $\text{I4}{}_1\text{a}\text{, Z = 4}$. The crystal structure was determined from single-crystal X-ray diffraction data and refined to a conventional R factor of 0.054. Palladium has a square planar sulfur coordination with PdS distances = 2.33 Å. Uranium is coordinated with eight sulfur atoms, with a mean US distance of 2.83 Å characteristic of uranium in the tetravalent state.