Poly[[diaqua(mu3-2,2-dimethylmalonato)cadmium(II)] tetrahydrate]

In the title complex, {[Cd(C(5)H(6)O(4))(H(2)O)(2)].4H(2)O}(n), the dimethylmalonate-cadmium metal-organic framework co-exists with an extended structure of water molecules, which resembles a sodalite-type framework. In the asymmetric unit, there are five independent solvent water molecules, two of which are in special positions. The Cd atoms are eight-coordinated in a distorted square-antiprismatic geometry by six O atoms of three different dimethylmalonate groups and by two water molecules, and form a two-dimensional honeycomb layer parallel to the bc plane. Two such layers sandwich the hydrogen-bonded water layer, which has a sodalite-type structure with truncated sodalite units composed of coordinated and solvent water molecules. This work is the first example of a dimethylmalonate cadmium complex containing truncated sodalite-type water clusters.