Decaaquabis(mu3-4-hydroxypyridine-2,6-dicarboxylato)bis(4-hydroxypyridine-2,6-dicarboxylato)tetramanganese(II) 3.34-hydrate: a new three-dimensional open metal-organic framework based on a tetranuclear MnII complex of chelidamic acid and undecameric stitching water clusters

4-Hydroxypyridine-2,6-dicarboxylic acid (chelidamic acid, cdaH3) reacts with MnCl2.2H2O in the presence of 2-amino- 4-methylpyrimidine in water to afford the tetranuclear title complex, [Mn4(C8H3NO5)4(H2O)10].3.34H2O, built through carboxylate bridging. The tetranuclear complex sits on a centre of inversion at (1 2, 1 2, 1 2). In the crystal, discrete undecameric (H2O)10.34 water clusters (involving both coordinated and uncoordinated water molecules, with one site of an uncoordinated water molecule not fully occupied) assemble these tetranuclear MnII complex units via an intricate array of hydrogen bonding into an overall three-dimensional network. The degree of structuring of the (H2O)10.34 supramolecular association of water molecules observed in the present compound, imposed by its environment and vice versa, will be discussed in comparison to that observed for the (H2O)14 supramolecular clusters in the case of the dinuclear complex [Mn2(cdaH)2(H2O)4].4H2O [Ghosh et al. (2005). Inorg. Chem. 44, 3856–3862].