Synthesis,Crystal Structure and Magnetism of the New Oxysulfide Ce3NbO4S3

The orange cerium‐niobium‐oxysulfide Ce₃NbO₄S₃ was synthesized by the solid state reaction of CeO₂, Ce‐metal, Nb₂O₅ and sulfur at 1100 °C. The crystal structure has orthorhombic symmetry (space group Pbam, a = 7.055(1), b = 14.571(3), c = 7.627(2) Å, Z = 4) and contains isolated Nb₂S₄O₆]^10? ions consisting of two strongly distorted, edge sharing NbO₃SS_2/2 octahedra. Niobium is connected to three oxygen and three sulfur atoms. The cerium atoms are eightfold coordinated by oxygen and sulfur atoms. Certain oxygen and sulfur atoms are not connected to niobium, but exclusively surrounded by cerium. By connecting these cation polyhedra, one recognizes layers of polycations perpendicular to the c‐axis. The magnetic susceptibility shows Curie‐Weiss behavior with an effective magnetic moment μ_eff = 2.63(1) μ_B/Ce in agreement with Ce³⁺. A Weiss‐constant θ_p = –12(1) K indicates weak antiferromagnetic coupling. No magnetic ordering was detected above 2 K.