CsTlI4 crystallizes in the monoclinic P2_1/c space group. Cs(1) is bonded in a 8-coordinate geometry to two equivalent I(2), three equivalent I(3), and three equivalent I(4) atoms. Tl(1) is bonded in a tetrahedral geometry to one I(1), one I(2), one I(3), and one I(4) atom. There are four inequivalent I sites. In the first I site, I(1) is bonded in a single-bond geometry to one Tl(1) atom. In the second I site, I(2) is bonded in a distorted single-bond geometry to two equivalent Cs(1) and one Tl(1) atom. In the third I site, I(3) is bonded in a 1-coordinate geometry to three equivalent Cs(1) and one Tl(1) atom. In the fourth I site, I(4) is bonded to three equivalent Cs(1) and one Tl(1) atom to form a mixture of distorted edge and corner-sharing ICs3Tl trigonal pyramids.
CsTlI4 crystallizes in the monoclinic P2_1/c space group. Cs(1) is bonded in a 8-coordinate geometry to two equivalent I(2), three equivalent I(3), and three equivalent I(4) atoms. There is one shorter (4.14 Å) and one longer (4.33 Å) Cs(1)-I(2) bond length. There are a spread of Cs(1)-I(3) bond distances ranging from 4.11-4.52 Å. There are a spread of Cs(1)-I(4) bond distances ranging from 4.24-4.28 Å. Tl(1) is bonded in a tetrahedral geometry to one I(1), one I(2), one I(3), and one I(4) atom. The Tl(1)-I(1) bond length is 2.82 Å. The Tl(1)-I(2) bond length is 2.83 Å. The Tl(1)-I(3) bond length is 2.85 Å. The Tl(1)-I(4) bond length is 2.85 Å. There are four inequivalent I sites. In the first I site, I(1) is bonded in a single-bond geometry to one Tl(1) atom. In the second I site, I(2) is bonded in a distorted single-bond geometry to two equivalent Cs(1) and one Tl(1) atom. In the third I site, I(3) is bonded in a 1-coordinate geometry to three equivalent Cs(1) and one Tl(1) atom. In the fourth I site, I(4) is bonded to three equivalent Cs(1) and one Tl(1) atom to form a mixture of distorted edge and corner-sharing ICs3Tl trigonal pyramids.