Cs3LaI6 crystallizes in the tetragonal P4_2/m space group. There are two inequivalent Cs sites. In the first Cs site, Cs(1) is bonded in a body-centered cubic geometry to eight equivalent I(1) atoms. In the second Cs site, Cs(2) is bonded in a 10-coordinate geometry to four equivalent I(2) and six equivalent I(1) atoms. La(1) is bonded in an octahedral geometry to two equivalent I(2) and four equivalent I(1) atoms. There are two inequivalent I sites. In the first I site, I(1) is bonded in a 6-coordinate geometry to two equivalent Cs(1), three equivalent Cs(2), and one La(1) atom. In the second I site, I(2) is bonded in a 5-coordinate geometry to four equivalent Cs(2) and one La(1) atom.
Cs3LaI6 crystallizes in the tetragonal P4_2/m space group. There are two inequivalent Cs sites. In the first Cs site, Cs(1) is bonded in a body-centered cubic geometry to eight equivalent I(1) atoms. There are four shorter (3.94 Å) and four longer (3.96 Å) Cs(1)-I(1) bond lengths. In the second Cs site, Cs(2) is bonded in a 10-coordinate geometry to four equivalent I(2) and six equivalent I(1) atoms. There are a spread of Cs(2)-I(2) bond distances ranging from 3.87-4.47 Å. There are a spread of Cs(2)-I(1) bond distances ranging from 4.03-4.42 Å. La(1) is bonded in an octahedral geometry to two equivalent I(2) and four equivalent I(1) atoms. Both La(1)-I(2) bond lengths are 3.17 Å. All La(1)-I(1) bond lengths are 3.18 Å. There are two inequivalent I sites. In the first I site, I(1) is bonded in a 6-coordinate geometry to two equivalent Cs(1), three equivalent Cs(2), and one La(1) atom. In the second I site, I(2) is bonded in a 5-coordinate geometry to four equivalent Cs(2) and one La(1) atom.