Tetrasodium (dihydrogenheptaoxidodigermanato)bis(dihydrogentetraoxidogermanato)dicopper(II) monohydrate

In the hydro/solvothermally synthesized title compound, Na4[Cu2(H2Ge2O7)(H2GeO4)2]·H2O, the framework building units include CuO4, GeO2(OH)2 and GeO3(OH) tetrahedra, the latter being condensed into H2Ge2O74− dimers. All the tetrahedra are connected by corner-sharing into four-membered-ring (4MR) secondary building units containing two CuO4, one GeO2(OH)2 and one GeO3(OH) entity. The 4MRs form chains by corner-sharing the Cu unit and adjacent chains are linked by H2Ge2O74− dimers, generating layers containing ten-membered rings. Three sodium cations (one with site symmetry overline{1} and one with site symmetry 2) and a water molecule (O-atom site symmetry 2) complete the structure. A network of O—H...O hydrogen bonds helps to consolidate the packing.