Cs2TmCl4 is (La,Ba)CuO4 structured and crystallizes in the tetragonal I4/mmm space group. Cs(1) is bonded in a 9-coordinate geometry to four equivalent Cl(2) and five equivalent Cl(1) atoms. Tm(1) is bonded to two equivalent Cl(1) and four equivalent Cl(2) atoms to form corner-sharing TmCl6 octahedra. The corner-sharing octahedra are not tilted. There are two inequivalent Cl sites. In the first Cl site, Cl(2) is bonded to four equivalent Cs(1) and two equivalent Tm(1) atoms to form distorted ClCs4Tm2 octahedra that share corners with two equivalent Cl(2)Cs4Tm2 octahedra, corners with twelve equivalent Cl(1)Cs5Tm octahedra, edges with two equivalent Cl(2)Cs4Tm2 octahedra, faces with four equivalent Cl(2)Cs4Tm2 octahedra, and faces with four equivalent Cl(1)Cs5Tm octahedra. The corner-sharing octahedral tilt angles range from 0-56°. In the second Cl site, Cl(1) is bonded to five equivalent Cs(1) and one Tm(1) atom to form distorted ClCs5Tm octahedra that share corners with five equivalent Cl(1)Cs5Tm octahedra, corners with twelve equivalent Cl(2)Cs4Tm2 octahedra, edges with eight equivalent Cl(1)Cs5Tm octahedra, and faces with four equivalent Cl(2)Cs4Tm2 octahedra. The corner-sharing octahedral tilt angles range from 0-56°.
Cs2TmCl4 is (La,Ba)CuO4 structured and crystallizes in the tetragonal I4/mmm space group. Cs(1) is bonded in a 9-coordinate geometry to four equivalent Cl(2) and five equivalent Cl(1) atoms. All Cs(1)-Cl(2) bond lengths are 3.64 Å. There is one shorter (3.54 Å) and four longer (3.77 Å) Cs(1)-Cl(1) bond lengths. Tm(1) is bonded to two equivalent Cl(1) and four equivalent Cl(2) atoms to form corner-sharing TmCl6 octahedra. The corner-sharing octahedra are not tilted. Both Tm(1)-Cl(1) bond lengths are 2.69 Å. All Tm(1)-Cl(2) bond lengths are 2.66 Å. There are two inequivalent Cl sites. In the first Cl site, Cl(2) is bonded to four equivalent Cs(1) and two equivalent Tm(1) atoms to form distorted ClCs4Tm2 octahedra that share corners with two equivalent Cl(2)Cs4Tm2 octahedra, corners with twelve equivalent Cl(1)Cs5Tm octahedra, edges with two equivalent Cl(2)Cs4Tm2 octahedra, faces with four equivalent Cl(2)Cs4Tm2 octahedra, and faces with four equivalent Cl(1)Cs5Tm octahedra. The corner-sharing octahedral tilt angles range from 0-56°. In the second Cl site, Cl(1) is bonded to five equivalent Cs(1) and one Tm(1) atom to form distorted ClCs5Tm octahedra that share corners with five equivalent Cl(1)Cs5Tm octahedra, corners with twelve equivalent Cl(2)Cs4Tm2 octahedra, edges with eight equivalent Cl(1)Cs5Tm octahedra, and faces with four equivalent Cl(2)Cs4Tm2 octahedra. The corner-sharing octahedral tilt angles range from 0-56°.