Abstract: | RbFeBP2O8(OH)]: A New Borophosphate Containing Open-Branched Tetrahedral Vierer-Einfach Chains RbFeBP2O8(OH)] is formed under mild hydrothermal conditions (T = 165–170 °C) from a mixture of RbOH(aq), FeCl2 · 4 H2O, H3BO3 and H3PO4. The crystal structure of the monoclinic compound was solved by x-ray single crystal methods (space group P21/c, No. 14): a = 935.8(5) pm, b = 833.9(6) pm, c = 965.6(5) pm; β = 101.69(4)°; Z = 4. The anionic partial structure contains open-branched vierer-einfach chains BP2O8(OH)]4–, which are formed by alternating borate and phosphate tetrahedra sharing common corners. Fe3+ is in an octahedral coordination (FeO5(OH)), while Rb+ is irregularly coordinated by ten oxygen-functions of neighbouring tetrahedra. |