Cs2Hg3H2OI8 crystallizes in the monoclinic Cm space group. Cs(1) is bonded in a 9-coordinate geometry to one O(1), one I(1), one I(4), one I(5), two equivalent I(2), and three equivalent I(3) atoms. There are two inequivalent Hg sites. In the first Hg site, Hg(1) is bonded to one I(3), one I(4), and two equivalent I(2) atoms to form corner-sharing HgI4 tetrahedra. In the second Hg site, Hg(2) is bonded to one I(1), one I(5), and two equivalent I(4) atoms to form corner-sharing HgI4 tetrahedra. There are two inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(1) atom. In the second H site, H(2) is bonded in a single-bond geometry to one O(1) atom. O(1) is bonded in a water-like geometry to two equivalent Cs(1), one H(1), and one H(2) atom. There are five inequivalent I sites. In the first I site, I(1) is bonded in a distorted single-bond geometry to two equivalent Cs(1) and one Hg(2) atom. In the second I site, I(2) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Cs(1) and two equivalent Hg(1) atoms. In the third I site, I(3) is bonded to three equivalent Cs(1) and one Hg(1) atom to form a mixture of distorted edge and corner-sharing ICs3Hg trigonal pyramids. In the fourth I site, I(4) is bonded in a 3-coordinate geometry to one Cs(1), one Hg(1), and one Hg(2) atom. In the fifth I site, I(5) is bonded in a 3-coordinate geometry to two equivalent Cs(1) and one Hg(2) atom.
Cs2Hg3H2OI8 crystallizes in the monoclinic Cm space group. Cs(1) is bonded in a 9-coordinate geometry to one O(1), one I(1), one I(4), one I(5), two equivalent I(2), and three equivalent I(3) atoms. The Cs(1)-O(1) bond length is 3.31 Å. The Cs(1)-I(1) bond length is 4.19 Å. The Cs(1)-I(4) bond length is 4.20 Å. The Cs(1)-I(5) bond length is 4.13 Å. There is one shorter (4.29 Å) and one longer (4.44 Å) Cs(1)-I(2) bond length. There are a spread of Cs(1)-I(3) bond distances ranging from 4.10-4.27 Å. There are two inequivalent Hg sites. In the first Hg site, Hg(1) is bonded to one I(3), one I(4), and two equivalent I(2) atoms to form corner-sharing HgI4 tetrahedra. The Hg(1)-I(3) bond length is 2.76 Å. The Hg(1)-I(4) bond length is 2.85 Å. There is one shorter (2.91 Å) and one longer (2.95 Å) Hg(1)-I(2) bond length. In the second Hg site, Hg(2) is bonded to one I(1), one I(5), and two equivalent I(4) atoms to form corner-sharing HgI4 tetrahedra. The Hg(2)-I(1) bond length is 2.75 Å. The Hg(2)-I(5) bond length is 2.75 Å. Both Hg(2)-I(4) bond lengths are 3.02 Å. There are two inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(1) atom. The H(1)-O(1) bond length is 0.98 Å. In the second H site, H(2) is bonded in a single-bond geometry to one O(1) atom. The H(2)-O(1) bond length is 0.98 Å. O(1) is bonded in a water-like geometry to two equivalent Cs(1), one H(1), and one H(2) atom. There are five inequivalent I sites. In the first I site, I(1) is bonded in a distorted single-bond geometry to two equivalent Cs(1) and one Hg(2) atom. In the second I site, I(2) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Cs(1) and two equivalent Hg(1) atoms. In the third I site, I(3) is bonded to three equivalent Cs(1) and one Hg(1) atom to form a mixture of distorted edge and corner-sharing ICs3Hg trigonal pyramids. In the fourth I site, I(4) is bonded in a 3-coordinate geometry to one Cs(1), one Hg(1), and one Hg(2) atom. In the fifth I site, I(5) is bonded in a 3-coordinate geometry to two equivalent Cs(1) and one Hg(2) atom.