Synthesis, Crystal Structure and Magnetism of the New Oxysulfide Ce 3 NbO 4 S 3

The orange cerium‐niobium‐oxysulfide Ce 3 NbO 4 S 3 was synthesized by the solid state reaction of CeO 2 , Ce‐metal, Nb 2 O 5 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 [Nb 2 S 4 O 6 ] 10− ions consisting of two strongly distorted, edge sharing NbO 3 SS 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 ²∞ [(Ce₆S₂O₂)¹⁰⁺] 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 Ce 3+ . A Weiss‐constant θ p = –12(1) K indicates weak antiferromagnetic coupling. No magnetic ordering was detected above 2 K.