Cs2O11I4 crystallizes in the hexagonal P6_3 space group. There are two inequivalent Cs sites. In the first Cs site, Cs(1) is bonded in a 9-coordinate geometry to three equivalent O(1), three equivalent O(2), and three equivalent O(5) atoms. In the second Cs site, Cs(2) is bonded in a 9-coordinate geometry to three equivalent O(1), three equivalent O(2), and three equivalent O(5) atoms. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one Cs(1), one Cs(2), and one I(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to one Cs(1), one Cs(2), and one I(1) atom. In the third O site, O(3) is bonded in a trigonal planar geometry to three equivalent I(1) atoms. In the fourth O site, O(4) is bonded in a trigonal planar geometry to three equivalent I(1) atoms. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to one Cs(1), one Cs(2), one I(1), and one I(2) atom. There are two inequivalent I sites. In the first I site, I(1) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(3), one O(4), and one O(5) atom. In the second I site, I(2) is bonded in a distorted trigonal non-coplanar geometry to three equivalent O(5) atoms.
Cs2O11I4 crystallizes in the hexagonal P6_3 space group. There are two inequivalent Cs sites. In the first Cs site, Cs(1) is bonded in a 9-coordinate geometry to three equivalent O(1), three equivalent O(2), and three equivalent O(5) atoms. All Cs(1)-O(1) bond lengths are 3.30 Å. All Cs(1)-O(2) bond lengths are 3.17 Å. All Cs(1)-O(5) bond lengths are 3.43 Å. In the second Cs site, Cs(2) is bonded in a 9-coordinate geometry to three equivalent O(1), three equivalent O(2), and three equivalent O(5) atoms. All Cs(2)-O(1) bond lengths are 3.26 Å. All Cs(2)-O(2) bond lengths are 3.26 Å. All Cs(2)-O(5) bond lengths are 3.21 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one Cs(1), one Cs(2), and one I(1) atom. The O(1)-I(1) bond length is 1.80 Å. In the second O site, O(2) is bonded in a distorted single-bond geometry to one Cs(1), one Cs(2), and one I(1) atom. The O(2)-I(1) bond length is 1.79 Å. In the third O site, O(3) is bonded in a trigonal planar geometry to three equivalent I(1) atoms. All O(3)-I(1) bond lengths are 2.13 Å. In the fourth O site, O(4) is bonded in a trigonal planar geometry to three equivalent I(1) atoms. All O(4)-I(1) bond lengths are 2.12 Å. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to one Cs(1), one Cs(2), one I(1), and one I(2) atom. The O(5)-I(1) bond length is 2.66 Å. The O(5)-I(2) bond length is 1.82 Å. There are two inequivalent I sites. In the first I site, I(1) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(3), one O(4), and one O(5) atom. In the second I site, I(2) is bonded in a distorted trigonal non-coplanar geometry to three equivalent O(5) atoms.