Metal-phenoxyalkanoic acid interactions Part 10. Crystal and molecular structures of catena-[tetraaqua(4-carboxylato-phenoxyacetato)manganese(II)], tetraaquabis(4-carboxyphenoxyacetato)nickel(II) and tetraaquabis(4-carboxyphenoxyacetato)cobalt(II)

The crystal structures of two metal(II) complexes of 4-carboxyphenoxyacetic acid have been determined by X-ray methods. The first, catena[tetraaqua(4-carboxylato-phenoxyacetato)manganese(II), (1) forms crystals which are orthorhombic, space group Pbca, with 8 molecules in a unit cell of dimensions a = 10.356(2), b = 9.086(2), c = 25.673(8) Å. It has a polymeric structure involving both cis-related carboxylate groups and four water molecules about a slightly distorted octahedron. The mean MnO (water) distance is 2.214(7) Å, while the MnO (carboxylate) distances are 2.147(6) and 2.111(7) Å. Tetraaquabis(4-carboxyphenoxyacetato)nickel(II) (2) is triclinic, space group P1 with one molecule in the cell, dimensions a = 4.896(2), b = 5.679(2), c = 18.403(6) Å, α = 93.75(3), β = 91.78(3), γ = 95.76(2). The centrosymmetric complex units are discrete monomers with unidentate trans-related acid ligands bonded through the phenoxy carboxylate oxygen [NiO, 2.058(3) Å]. The NiO (water) distance is 2.055(4) Å. Single crystal diffractometry and elemental analysis have been used to prove that the Co(II) (3) analogue is isomorphous and isostructural with the Ni(II) complex. The p-carboxy group of one molecule is hydrogen bonded about a centre of symmetry to another p-carboxy group. © 1984.