Abstract
Potassium indium bis-[hydrogen arsenate(V)], KIn(HAsO(4))(2), rubidium indium bis-[hydrogen arsenate(V)], RbIn(HAsO(4))(2), and caesium indium bis-[hydrogen arsenate(V)], CsIn(HAsO(4))(2), were grown under mild hydro-thermal conditions (T = 493 K, 7-8 d). KIn(HAsO(4))(2) adopts the KSc(HAsO(4))(2) structure type (space group C2/c), while RbIn(HAsO(4))(2) and CsIn(HAsO(4))(2) crystallize in the space group R-3c and are the first arsenate representatives of the RbFe(HPO(4))(2) structure type. All three compounds have tetra-hedral-octa-hedral framework topologies. The M(+) cations, located in voids of the respective framework, are slightly disordered in RbIn(HAsO(4))(2). In KIn(HAsO(4))(2), there is a second K-atom position with a very low occupancy, which may suggest that the K atom can easily move in the channels extending along [101].