catena-Poly[[[aqua(7-hydroxy-2H-1-benzopyran-2-one)sodium]-di-μ-aqua] 2-oxo-2H-1-benzopyran-7-olate monohydrate]

The asymmetric unit of the title compound, {[Na(C9H6O3)(H2O)3](C9H5O3)·H2O}n, contains two crystallographically independent Na atoms, two 7-hydroxycoumarin ligands, six coordinated water molecules, two 7-hydroxycoumarin anions and two uncoordinated water molecules. Both Na atoms exhibit a distorted octahedral coordination geometry and are coordinated by five water O atoms and the terminal O atom from a 7-hydroxycoumarin ligand. Four of the water molecules are bridging, whereas the fifth is terminal. Na—O bond distances are in the range 2.288 (2)–2.539 (2) Å. In the chains, extending parallel to [100], adjacent Na atoms are separated by 3.60613 (7) Å. The uncoordinated water molecules and 7-hydroxycoumarin phenolate anions are located between the chains and are hydrogen bonded to the chains.