The crystal structure of Yb2(SO4)3·3H2O and its decomposition product, β-Yb2(SO4)3

Yb2(SO4)3·3H2O, synthesised by hydrothermal methods at 220(2) °C, has been investigated by single crystal X-ray diffraction. Yb2(SO4)3·3H2O crystallises in space group Cmc21 and is isostructural with Lu2(SO4)3·3H2O. The crystal structure has been refined to R1=0.0145 for 3412 reflections [Fo>3σ(F)], and 0.0150 for all 3472 reflections. The structure of Yb2(SO4)3·3H2O is a complex framework of YbO6 octahedra, YbO8 and YbO5(H2O)3 polyhedra and SO4 tetrahedra. Thermal data shows that Yb2(SO4)3·3H2O decomposes between 120 and 190 °C to form β-Yb2(SO4)3. The structure of a twinned crystal of β-Yb2(SO4)3 was solved and refined using an amplimode refinement in R3c with an R1=0.0755 for 8944 reflections [Fo>3σ(F)], and 0.1483 for all 16,361 reflections. β-Yb2(SO4)3 has a unique structural topology based on a 3D network of pinwheels.