inorganic compounds
The monoclinic room-temperature structure of tricaesium hydrogen bis[tetraoxoselenate(2−)] was refined from high-resolution neutron powder diffraction data. Special emphasis was given to the precise location of the H atom and the determination of the hydrogen-bond network. A Fourier analysis clearly shows that the H atom is distributed over two symmetry-equivalent positions of half occupancy [HH = 0.52 (2) Å] around an inversion centre. The hydrogen bridge is non-linear [O-HO = 173 (2)°] with an OO distance of 2.506 (7) Å.