Two new Rb–Ga arsenates: RbGa(HAsO(4))(2) and RbGa(2)As(HAsO(4))(6)

The crystal structures of hydro­thermally synthesized (T = 493 K, 7–9 d) rubidium gallium bis­[hydrogenarsenate(V)], RbGa(HAsO(4))(2), and rubidium digallium arsenic(V) hexa­[hydrogenarsenate(V)], RbGa(2)As(HAsO(4))(6), were solved by single-crystal X-ray diffraction. Both compounds have tetra­hedral–octa­hedral framework topologies. The M (+) cations are located in channels of the respective framework. RbGa(HAsO(4))(2) crystallizes in the RbFe(HPO(4))(2) structure type (R [Image: see text] c), while RbGa(2)As(HAsO(4))(6) adopts the structure type of RbAl(2)As(HAsO(4))(6) (R [Image: see text] c), which represents a modification of the RbFe(HPO(4))(2) structure type. In this modification, one third of the M (3+)O(6) octa­hedra are replaced by AsO(6) octa­hedra, and two thirds of the voids in the structure, which are usually filled by M (+) cations, remain empty to achieve charge balance.