Three-Dimensional Polymers with Metal–Oxygen and Metal–Ligand Chains: [Mn(II)(4,4′-bipy)2(Cr2O7)(H2O)2] and [Co(II)(4,4′-bipy)2(Cr2O7)]

Reaction of aqueous solutions of [M(H2O)6](ClO4)2 (M = Mn(II) and Co(II)) and dichromate ion with 4,4′-bipy provides coordination polymers with metal–oxygen chain. The structure of [Mn(4,4′-bipy)2(Cr2O7)(H2O)2] reveals the 2D sheet structure which is constructed by hydrogen bonding between 1D chains, while [Co(4,4′-bipy)2(Cr2O7)] shows hybrid 3D polymers which have metal–bipy square grid and the dichromate pillar forms an interpenetrated cuboidal 3D structure.