Abstract
The title compound, nonasodium chromium(III) hexakis[molybdate(VI)], beta-Na9CrMo6O24, was prepared by solid-state reactions. This alluaudite-type structure is constituted of infinite layers formed by links between M2O10 (M = C/Na) dimers and MoO4 tetrahedra. The Na+ and Cr3+ cations are located in the same site with, respectively, 0.25 and 0.75 occupancies. The layers are connected to each other through MoO4 sharing corners, resulting an in open three-dimensional framework with hexagonal-form cavities occupied by Na+ cations. The proposed structural model is supported by charge-distribution (CHARDI) and bond-valence-sum (BVS) analysis. All atoms are on general positions except for one Mo, two Na (site symmetry 2) and another Na site (site symmetry (1) over bar). A comparison is made with the similar structures Na4Co(MoO4)(3), Na2Ni(MoO4)(2), Cu1.35Fe3(PO4)(3) and NaAgFeMn2(PO4)(3).