Octaammonium Diaquahexa-Μ2-oxalato-dioxalatotetracopper(ii) Tetrahydrate

In the structure of the title compound, (NH4)8[Cu4(C2O4)8(H2O)2]·4H2O, isolated tetramers of [Cu(ox)2]2+ (ox is oxalate) are present. Each CuII ion coordinates to four O atoms in two oxalate ligands and to two more distant O atoms in a neighbouring oxalate ligand or a water molecule. An extensive hydrogen-bonding network connects the tetramers to two unique solvent water molecules and four ammonium ions.