CsTm(WO4)2 crystallizes in the trigonal P-3m1 space group. Cs(1) is bonded to six equivalent O(1) and six equivalent O(2) atoms to form CsO12 cuboctahedra that share edges with six equivalent Cs(1)O12 cuboctahedra, edges with six equivalent W(1)O4 tetrahedra, and faces with two equivalent Tm(1)O6 octahedra. Tm(1) is bonded to six equivalent O(1) atoms to form TmO6 octahedra that share corners with six equivalent W(1)O4 tetrahedra and faces with two equivalent Cs(1)O12 cuboctahedra. W(1) is bonded to one O(2) and three equivalent O(1) atoms to form WO4 tetrahedra that share corners with three equivalent Tm(1)O6 octahedra and edges with three equivalent Cs(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 19°. There are two inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 150 degrees geometry to one Cs(1), one Tm(1), and one W(1) atom. In the second O site, O(2) is bonded in a single-bond geometry to three equivalent Cs(1) and one W(1) atom.
CsTm(WO4)2 crystallizes in the trigonal P-3m1 space group. Cs(1) is bonded to six equivalent O(1) and six equivalent O(2) atoms to form CsO12 cuboctahedra that share edges with six equivalent Cs(1)O12 cuboctahedra, edges with six equivalent W(1)O4 tetrahedra, and faces with two equivalent Tm(1)O6 octahedra. All Cs(1)-O(1) bond lengths are 3.26 Å. All Cs(1)-O(2) bond lengths are 3.48 Å. Tm(1) is bonded to six equivalent O(1) atoms to form TmO6 octahedra that share corners with six equivalent W(1)O4 tetrahedra and faces with two equivalent Cs(1)O12 cuboctahedra. All Tm(1)-O(1) bond lengths are 2.20 Å. W(1) is bonded to one O(2) and three equivalent O(1) atoms to form WO4 tetrahedra that share corners with three equivalent Tm(1)O6 octahedra and edges with three equivalent Cs(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 19°. The W(1)-O(2) bond length is 1.75 Å. All W(1)-O(1) bond lengths are 1.80 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 150 degrees geometry to one Cs(1), one Tm(1), and one W(1) atom. In the second O site, O(2) is bonded in a single-bond geometry to three equivalent Cs(1) and one W(1) atom.