Crystal structures of dimetal terephthalate di­hydroxides, M (2)(C(8)H(4)O(4))(OH)(2) (M = Co, Ni, Zn) from powder diffraction data and DFT calculations

The crystal structure of poly[di­hydroxido(μ(6)-terepthalato)dizinc], [Zn(2)(C(8)H(4)O(4))(OH)(2)]( n ), was solved and refined using synchrotron powder data, and the structures of the isostructural Co and Ni analogues were refined using laboratory powder X-ray data. The structure of [Co(2)(C(8)H(4)O(4))(OH)(2)]( n ) has been reported previously in space group C2/m, which yields disordered terephthalate anions. Doubling the c-axis of that cell results in an ordered model in space group C2/c. The octa­hedral MO(6) coordination polyhedra of the metal cations share edges, forming chains running parallel to the b-axis direction. These chains share corners (hydroxyl groups), forming layers lying perpendicular to the a-axis direction.