CsSnI3 is Orthorhombic Perovskite structured and crystallizes in the orthorhombic Pnma space group. Cs(1) is bonded in a 7-coordinate geometry to three equivalent I(2) and four equivalent I(1) atoms. Sn(1) is bonded to two equivalent I(2) and four equivalent I(1) atoms to form corner-sharing SnI6 octahedra. The corner-sharing octahedral tilt angles range from 6-22°. There are two inequivalent I sites. In the first I site, I(1) is bonded to two equivalent Cs(1) and two equivalent Sn(1) atoms to form distorted ICs2Sn2 trigonal pyramids that share corners with four equivalent I(2)Cs3Sn2 square pyramids, corners with ten equivalent I(1)Cs2Sn2 trigonal pyramids, edges with three equivalent I(2)Cs3Sn2 square pyramids, and  an edgeedge with one I(1)Cs2Sn2 trigonal pyramid. In the second I site, I(2) is bonded to three equivalent Cs(1) and two equivalent Sn(1) atoms to form distorted ICs3Sn2 square pyramids that share corners with four equivalent I(2)Cs3Sn2 square pyramids, corners with eight equivalent I(1)Cs2Sn2 trigonal pyramids, edges with two equivalent I(2)Cs3Sn2 square pyramids, and edges with six equivalent I(1)Cs2Sn2 trigonal pyramids.
CsSnI3 is Orthorhombic Perovskite structured and crystallizes in the orthorhombic Pnma space group. Cs(1) is bonded in a 7-coordinate geometry to three equivalent I(2) and four equivalent I(1) atoms. There are a spread of Cs(1)-I(2) bond distances ranging from 4.11-4.38 Å. There are two shorter (4.00 Å) and two longer (4.05 Å) Cs(1)-I(1) bond lengths. Sn(1) is bonded to two equivalent I(2) and four equivalent I(1) atoms to form corner-sharing SnI6 octahedra. The corner-sharing octahedral tilt angles range from 6-22°. Both Sn(1)-I(2) bond lengths are 3.16 Å. There are two shorter (3.13 Å) and two longer (3.14 Å) Sn(1)-I(1) bond lengths. There are two inequivalent I sites. In the first I site, I(1) is bonded to two equivalent Cs(1) and two equivalent Sn(1) atoms to form distorted ICs2Sn2 trigonal pyramids that share corners with four equivalent I(2)Cs3Sn2 square pyramids, corners with ten equivalent I(1)Cs2Sn2 trigonal pyramids, edges with three equivalent I(2)Cs3Sn2 square pyramids, and  an edgeedge with one I(1)Cs2Sn2 trigonal pyramid. In the second I site, I(2) is bonded to three equivalent Cs(1) and two equivalent Sn(1) atoms to form distorted ICs3Sn2 square pyramids that share corners with four equivalent I(2)Cs3Sn2 square pyramids, corners with eight equivalent I(1)Cs2Sn2 trigonal pyramids, edges with two equivalent I(2)Cs3Sn2 square pyramids, and edges with six equivalent I(1)Cs2Sn2 trigonal pyramids.