CsTmI3 is Orthorhombic Perovskite structured and crystallizes in the orthorhombic Pnma space group. Cs(1) is bonded in a 9-coordinate geometry to three equivalent I(2) and six equivalent I(1) atoms. Tm(1) is bonded to two equivalent I(2) and four equivalent I(1) atoms to form corner-sharing TmI6 octahedra. The corner-sharing octahedral tilt angles are 19°. There are two inequivalent I sites. In the first I site, I(1) is bonded to three equivalent Cs(1) and two equivalent Tm(1) atoms to form a mixture of distorted corner and edge-sharing ICs3Tm2 trigonal bipyramids. In the second I site, I(2) is bonded in a 4-coordinate geometry to three equivalent Cs(1) and two equivalent Tm(1) atoms.
CsTmI3 is Orthorhombic Perovskite structured and crystallizes in the orthorhombic Pnma space group. Cs(1) is bonded in a 9-coordinate geometry to three equivalent I(2) and six equivalent I(1) atoms. There are a spread of Cs(1)-I(2) bond distances ranging from 3.87-4.45 Å. There are a spread of Cs(1)-I(1) bond distances ranging from 3.94-4.13 Å. Tm(1) is bonded to two equivalent I(2) and four equivalent I(1) atoms to form corner-sharing TmI6 octahedra. The corner-sharing octahedral tilt angles are 19°. Both Tm(1)-I(2) bond lengths are 3.08 Å. There are two shorter (3.05 Å) and two longer (3.06 Å) Tm(1)-I(1) bond lengths. There are two inequivalent I sites. In the first I site, I(1) is bonded to three equivalent Cs(1) and two equivalent Tm(1) atoms to form a mixture of distorted corner and edge-sharing ICs3Tm2 trigonal bipyramids. In the second I site, I(2) is bonded in a 4-coordinate geometry to three equivalent Cs(1) and two equivalent Tm(1) atoms.