A monoclinic pseudopolymorph of manganese squarate dihydrate,Mn(μ‐C4O4)(H2O)2, built from cubic units

The structure of polyhexaaquatrimanganese(II)]‐tri‐μ‐squarato] monohydrate], {Mn₃(C₄O₄)₃(H₂O)₆]·H₂O}_n, synthesized hydrothermally, consists of a new three‐dimensional framework described by secondary building units (SBUs) containing two MnO₆ octahedra and three squarate groups in a cube‐shaped arrangement. In the asymmetric unit, one squarate group is located around an inversion centre (4a; 0, 0, 0), two Mn atoms 4d (, , 0) and 4c (, , 0)] are located on inversion centres and the third Mn atom is on a twofold axis (4e; 0, y, ). This report illustrates the concept of the SBU and the flexibility of the squarate spacer in the design of new porous topologies.