2,2'-Bipyridine-cyclo-pentane-1,2,3,4-tetra-carb-oxy-lic acid (1/1).

The asymmetric unit of the title compound, C(10)H(8)N(2)·C(9)H(10)O(8), contains a half-molecule of 2,2'-bipyridine and a half-molecule of 1,2,3,4-cyclopentanetetracarboxylic acid, both components being completed by crystallographic inversion symmetry. In the crystal, the mol-ecules are assembled into chains extending along [010] by O-H⋯N hydrogen bonds; adjacent chains are linked by O-H⋯O hydrogen bonds into a three-dimensional network.

Poly[[diaqua-μ(6)-succinato-di-μ(5)-succinato-didysprosium(III)] mono-hydrate].

The title compound, {[Dy(2)(C(4)H(4)O(4))(3)(H(2)O)(2)]·H(2)O}(n), is isostructural with other lanthanide succinates of the same formula. The Dy(III) atom is nine-coordinated in a tricapped trigonal-prismatic environment by eight O atoms, derived from six carboxyl-ate groups and a water mol-ecule. One of the independent succinate anions is located about a crystallographic inversion center and the uncoordinated water mol-ecule lies on a twofold axis.

Poly[hexa-aqua-bis-(μ(3)-hepta-nedioato-κO:O':O'')dimagnesium].

In the title compound, [Mg(2)(C(7)H(10)O(4))(2)(H(2)O)(6)](n), the Mg(II) ion is coordinated by three aqua ligands and three O atoms from three heptanedioato ligands in a distorted octa-hedral geometry. Each heptanedioato ligand bridges three Mg atoms, generating polymeric layers parallel to the bc plane. The polymeric layers related by translation along the a axis inter-act further via O-H⋯O hydrogen bonds, which consolidate the crystal packing.