Three three-dimensional anionic metal–organic frameworks with (4,8)-connected alb topology constructed from a semi-rigid ligand and polynuclear metal clusters

Three three-dimensional coordination polymers, namely, [NH2(CH3)2][Co2(MDIP)(OH)(H2O)]·C3H7NO·H2O (1), [NH2(CH3)2]2[Mn3(MDIP)2]·2C3H7NO (2), and [NH2(CH3)2][Mg3(MDIP)(HMDIP)(C3H7NO)]·4H2O (3) (DMF = N,N′-dimethylformamide), have been synthesized by the solvothermal reaction of Co(II), Mn(II), or Mg(II) salts with methylenediisophthalic acid (H4MDIP). All compounds have been characterized by thermogravimetric analysis, IR spectroscopy, elemental and single-crystal X-ray diffraction analyses. Complexes 1–3 are anionic frameworks with [NH2(CH3)2]+ ions occupying the voids, built upon tetra-, tri- and asymmetrical trimetallic cores, respectively. In particular, the asymmetrical trinuclear Mg(II) unit in complex 3 was scarcely observed. Topological analyses show that the three compounds possess binodal (4,8)-connected alb topology with a Schläfli symbol of (410.614.84)(45.6)2. Magnetic investigations indicate that antiferromagnetic couplings are dominant in compounds 1 and 2.