Syntheses and structures of three f-element selenite/hydroselenite compounds

The selenite/hydroselenite compounds Ce(SeO3)(HSeO3), Tb(SeO3)(HSeO3)·2H2O, and Cs[U(SeO3)(HSeO3)]·3H2O were synthesized by hydrothermal means at 453 K from the reaction of CeO2 or Tb4O7 or UO2 with SeO2 and CsCl (as a mineralizer). Ce(SeO3)(HSeO3) crystallizes in the non-centrosymmetric orthorhombic space group Pca21. The structure comprises a two-dimensional network of interconnected CeO10 bicapped distorted square antiprisms and SeO3 trigonal pyramids. Tb(SeO3)(HSeO3)·2H2O crystallizes in the non-centrosymmetric orthorhombic space group P212121. The structure features a two-dimensional layer of interconnected TbO8 distorted square antiprisms and SeO3 trigonal pyramids. Cs[U(SeO3)(HSeO3)]·3H2O crystallizes in the centrosymmetric monoclinic space group P21/n. The structure consists of two-dimensional layers of interconnected UO7 pentagonal bipyramids and SeO3 trigonal pyramids. The layers in all three structures are held together by hydrogen-bonding networks.