A non‐centrosymmetric polymorph of Gd3RuO7

A new non‐centrosymmetric modification has been found for trigadolinium ruthenium hepta­oxide, Gd3RuO7, crystallizing in the space group P21nb. The structure is composed of infinite single chains of corner‐linked [RuO6] octa­hedra embedded in the [Gd3O] matrix. The octa­hedra in the P21nb modification have two tilt systems about the a and c axes, in contrast to the previously reported Cmcm modification [Bontchev et al. (2000). Phys. Rev. B, 62, 12235–12240], with only one tilt system about the a axis. Changes in the coordination of Gd atoms in the title compound are closely related to the tilting mechanism about the c axis.