Pr₃InO: Re-assessment of the cubic Pr₃In structure

Single crystals of the title compound, tripraseodinium indium oxide, have been synthesized from a high-temperature reaction using a Pr-Cu eutectic mixture as flux. Based on its powder X-ray diffraction pattern, the product of the reaction was believed to be Pr3In with the long known cubic AuCu3 structure. However, structure refinements from single-crystal X-ray diffraction data confirmed that it is rather an oxygen-stabilized Pr3InO with the inverse perovskite structure (Pearsons code cP5). The latter structure can be described as being built of corner-sharing Pr6O octa-hedra with the In atoms occupying the cube-octa-hedral cavities. All three atoms in the asymmetric unit are in special positions: Pr 4/mm.m, In m m and O m m.