A novel three-dimensional Cd^II metal–organic framework based on [Cd₆(malonate)₆] metallomacrocycles with zeolite SOD (sodalite) topology: poly[ammine-μ₃-malonato-cadmium(II)]

A novel Cd^II metal–organic framework, [Cd(C₃H₂O₄)(NH₃)]_n, was synthesized by liquid diffusion conducted in the presence of ammonia. The Cd^II atom has seven-coordinate O₆N penta­gonal–bipyramidal geometry. Six Cd^II centers are joined by six malonate ligands to form an S₆-symmetric [Cd₆(malon­ate)₆] metallomacrocycle, which is further extended through a side-on chelating malonate ligand to form a three-dimensional network. Topologically, each Cd^II center is connected to four others to yield an infinite three-periodic four-coordinated SOD (sodalite) network with point symbol {4²·6⁴}. The overall network structure in the crystal is maintained and stabilized by the presence of N—H...O hydrogen bonds.