Crystal structure of BaMnB(2)O(5) containing structurally isolated manganese oxide sheets

In an attempt to search for mixed alkaline-earth and transition metal pyroborates, the title compound, barium manganese(II) pyroborate, has been synthesized by employing a flux method. The structure of BaMnB(2)O(5) is composed of MnO(5) square pyramids that form Mn(2)O(8) dimers by edge-sharing and of pyroborate units ([B(2)O(5)](4−)) that are composed of two corner-sharing trigonal–planar BO(3) units. These building blocks share corners to form (∞) (2)[MnB(2)O(5)](2−) layers extending parallel to (100). The Ba(2+) cations reside in the gap between two manganese pyroborate slabs with a coordination number of nine. The title compound forms an inter­esting spiral framework propagating along the 2(1) screw axis. The structure is characterized by two alternating layers, which is relatively rare among known transition-metal-based pyroborate compounds.