Crystal structure of the compounds La2Ge3O9 and Ce2Ge3O9 and their structural relationship to the tornebohmite type RE(2)Al(SiO4)(2)(OH)

La2Ge3O9 and Ce2Ge3O9 crystallize in space group A (1) over bar with a = 7.707(2) Angstrom, [7.684(3) Angstrom], b = 5.727(1) Angstrom, [5.705(2) Angstrom]; c = 16.797(2) Angstrom, [16.659(9) Angstrom]; alpha = 90.53(2)degrees, [90.56(3)degrees]; beta = 109.85(2)degrees, [109.55(3)degrees]; gamma = 88.68(2)degrees, [88.75(3)degrees]; and Z = 4. The structures have been determined from single crystal X-ray data. The final R-values are 0.0198 and 0.0252. The rare earth cations in both structures are surrounded by nine oxygen-atoms. The germanium atoms are coordinated by four, five and six oxygen-atoms.