Crystal structure of alluaudite-type KNa5Mn3(MoO4)6

The new phase potassium pentasodium trimanganese hexakis(molybdate), KNa<inf>5</inf>Mn<inf>3</inf>Mo<inf>6</inf>O<inf>24</inf>, has been synthesized using solid-state methods. The structure is composed of M<inf>2</inf>O<inf>10</inf> (M = Mn, Na) dimers and MoO<inf>4</inf> tetrahedra (point group symmetry 2) sharing corners and forming layers parallel to (100), which are linked via common corners of another type of MO<inf>4</inf> tetrahedra, forming a three-dimensional structure with two types of large channels along [[]001] in which two types of Na⁺ cations (one with site symmetry 2, one with 1¯) and K⁺ cations (site symmetry 2, half-occupation) are located. Mn²⁺ and the third type of Na⁺ cations are located at the same site M with occupancies of 0.75 and 0.25, respectively. A comparative structural description is provided between the structure of the title compound and those of the related phases Cu<inf>1.35</inf>Fe<inf>3</inf>(PO<inf>4</inf>)<inf>3</inf> and NaAg-FeMn<inf>2</inf>(PO<inf>4</inf>)<inf>3</inf>.