Copper-rich framework sulfides: A(4)Cu(8)Ge(3)S(12) (A = K, Rb) with cubic perovskite structure.

Two copper-rich open-framework sulfides, K(4)Cu(8)Ge(3)S(12) (1) and Rb(4)Cu(8)Ge(3)S(12) (2), have been synthesized under solvothermal conditions. Compounds 1 and 2 are isostructural and contain icosahedral [Cu(8)S(12)](16-) clusters as basic building blocks. These clusters are primitive cubic packed and connect to one another by discrete Ge(4+) ions to generate 3D copper-rich Cu-Ge-S framework and form 3D channels along 100 directions where the alkali metal cations reside. These two open-framework sulfides crystallize in cubic perovskite structure.