[Cu[C2(COO)2](H2O)3].H2O, the first copper complex of acetylenedicarboxylic acid

In the title compound, catena-poly[[[triaquacopper(II)]- micro -acetylenedicarboxylato-kappa(2)O:O"] hydrate], [[Cu(C(4)O(4))(H(2)O)(3)].H(2)O](n), the Cu(II) ion is coordinated by two monodentate carboxylate groups in trans positions and three water molecules, thus forming a fivefold coordination polyhedron that can be described as a distorted square pyramid. All atoms are located on general sites. The polyhedra are connected by bifunctional acetylenedicarboxylate ligands, to form almost linear chains parallel to [001]. Hydrogen bonds involving the non-coordinated water molecule connect these chains to form a three-dimensional framework.