CsY(SeO3)2 crystallizes in the cubic Pa-3 space group. Cs(1) is bonded to twelve equivalent O(1) atoms to form CsO12 cuboctahedra that share corners with twelve equivalent Cs(1)O12 cuboctahedra and edges with six equivalent Y(1)O6 octahedra. Y(1) is bonded to six equivalent O(1) atoms to form YO6 octahedra that share edges with six equivalent Cs(1)O12 cuboctahedra. Se(1) is bonded in a trigonal non-coplanar geometry to three equivalent O(1) atoms. O(1) is bonded in a distorted bent 150 degrees geometry to two equivalent Cs(1), one Y(1), and one Se(1) atom.
CsY(SeO3)2 crystallizes in the cubic Pa-3 space group. Cs(1) is bonded to twelve equivalent O(1) atoms to form CsO12 cuboctahedra that share corners with twelve equivalent Cs(1)O12 cuboctahedra and edges with six equivalent Y(1)O6 octahedra. There are six shorter (3.30 Å) and six longer (3.52 Å) Cs(1)-O(1) bond lengths. Y(1) is bonded to six equivalent O(1) atoms to form YO6 octahedra that share edges with six equivalent Cs(1)O12 cuboctahedra. All Y(1)-O(1) bond lengths are 2.28 Å. Se(1) is bonded in a trigonal non-coplanar geometry to three equivalent O(1) atoms. All Se(1)-O(1) bond lengths are 1.73 Å. O(1) is bonded in a distorted bent 150 degrees geometry to two equivalent Cs(1), one Y(1), and one Se(1) atom.