Poly[[diaqua-bis-(μ-oxalato-κ(4)O(1),O(2):O(1'),O(2'))bis-(μ(3)-5-oxidopyridin-1-ium-3-carboxyl-ato-κ(3)O(3):O(3'):O(5))diholmium(III)] dihydrate]

Crystal structure of poly[bis-(μ2-5-hydroxy-nicotinato-κ(2) N:O (3))zinc]

The title coordination polymer, [Zn(C₆H₄NO₃)₂]_n, was prepared under hydro­thermal conditions by the reaction of zinc nitrate with 5-hy­droxy­nicotinic acid in the presence of malonic acid. In the structure, the Zn^II ion is coordinated by two carboxyl­ate O atoms and two pyridine N atoms of four 5-hy­droxy­nicotinate ligands in a distorted tetra­hedral coordin­ation environment. The μ₂-bridging mode of each anion leads to the formation of a three-dimensional framework structure. Inter­molecular hydrogen bonds between the hy­droxy groups of one anion and the non-coordinating carboxyl­ate O atoms of neighbouring anions consolidate the crystal packing.