(a) Part of the crystal structure showing Mn1O6 and Mn2O6 octahedra sharing corners (polyhedral drawing). To distinguish the two types of bonds (short and long), one is highlighted with solid Mn—O bonds (short) and the other in dotted bonds (long). (b) The polyhedral units represent arsenic-centered oxygen tetrahedra. (c) The barium cation resides in a BaO8 environment. Displacement ellipsoids represent the 95% probability level.