Decaaquabis(μ3-4-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 Mn(II) complex of chelidamic acid and undecameric stitching water clusters.

4-Hydroxypyridine-2,6-dicarboxylic acid (chelidamic acid, cdaH(3)) reacts with MnCl(2)·2H(2)O in the presence of 2-amino-4-methylpyrimidine in water to afford the tetranuclear title complex, [Mn(4)(C(8)H(3)NO(5))(4)(H(2)O)(10)]·3.34H(2)O, built through carboxylate bridging. The tetranuclear complex sits on a centre of inversion at (½, ½, ½).

2-Amino-pyrimidinium 4-hy-droxy-pyridinium-2,6-dicarboxyl-ate monohydrate.

In the crystal structure of the title compound, C(4)H(6)N(3) (+)·C(7)H(4)NO(5) (-)·H(2)O, inter-molecular N-H⋯N, N-H⋯O and O-H⋯O hydrogen bonds link the cations and anions into almost planar sheets parallel to (102). These hydrogen-bonded sheets are packed into the crystal with the formation of centrosymmetric voids of 68 Å(3), which are filled by the water mol-ecules, each of which is disordered over four positions.