RbAuUSe3, CsAuUSe3, RbAuUTe3, and CsAuUTe3: Syntheses and structure; magnetic properties of RbAuUSe3

The compounds RbAuUSe3, CsAuUSe3, and RbAuUTe3 were synthesized at 1073 K from the reactions of U, Au, Q, and A 2Q 3 (A =Rb or Cs; Q =Se or Te). The compound CsAuUTe3 was synthesized at 1173 K from the reaction of U, Au, Te, and CsCl as a flux. These isostructural compounds crystallize in the KCuZrS3 structure type in space group Cmcm of the orthorhombic system. The structure consists of View the MathML source∞2[AuUQ3-] layers that contain nearly regular UQ6 octahedra and distorted AuQ4 tetrahedra. The infinite layers are separated by bicapped trigonal prismatic A cations. The magnetic behavior of RbAuUSe3 deviates significantly from Curie–Weiss behavior at low temperatures. For T>200 K, the values of the Curie constant C and the Weiss constant θp are 1.82(9) emu K mol−1 and −3.5(2)×102 K, respectively. The effective magnetic moment μeff is 3.81(9) μB. Formal oxidation states of A/Au/U/Q may be assigned as +1/+1/+4/−2, respectively.