Cs3LiI4 crystallizes in the monoclinic P2_1/m space group. There are three inequivalent Cs sites. In the first Cs site, Cs(1) is bonded to two equivalent I(1) and four equivalent I(2) atoms to form distorted CsI6 pentagonal pyramids that share corners with four equivalent Cs(3)I6 octahedra, corners with four equivalent Li(1)I4 tetrahedra, edges with two equivalent Cs(3)I6 octahedra, and faces with two equivalent Cs(1)I6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 40°. In the second Cs site, Cs(2) is bonded in a 6-coordinate geometry to six equivalent I(2) atoms. In the third Cs site, Cs(3) is bonded to two equivalent I(3) and four equivalent I(1) atoms to form CsI6 octahedra that share corners with four equivalent Cs(3)I6 octahedra, corners with four equivalent Cs(1)I6 pentagonal pyramids, corners with four equivalent Li(1)I4 tetrahedra, edges with two equivalent Cs(3)I6 octahedra, edges with two equivalent Cs(1)I6 pentagonal pyramids, and faces with two equivalent Cs(3)I6 octahedra. The corner-sharing octahedral tilt angles are 50°. Li(1) is bonded to two equivalent I(2) and two equivalent I(3) atoms to form LiI4 tetrahedra that share corners with four equivalent Cs(3)I6 octahedra, corners with four equivalent Cs(1)I6 pentagonal pyramids, and corners with two equivalent Li(1)I4 tetrahedra. The corner-sharing octahedral tilt angles are 70°. There are three inequivalent I sites. In the first I site, I(1) is bonded to two equivalent Cs(1) and four equivalent Cs(3) atoms to form distorted ICs6 pentagonal pyramids that share corners with four equivalent I(2)Cs5Li octahedra, corners with four equivalent I(1)Cs6 pentagonal pyramids, edges with two equivalent I(2)Cs5Li octahedra, edges with two equivalent I(1)Cs6 pentagonal pyramids, and faces with two equivalent I(1)Cs6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 39°. In the second I site, I(2) is bonded to two equivalent Cs(1), three equivalent Cs(2), and one Li(1) atom to form distorted ICs5Li octahedra that share corners with eight equivalent I(2)Cs5Li octahedra, corners with two equivalent I(1)Cs6 pentagonal pyramids, edges with four equivalent I(2)Cs5Li octahedra,  an edgeedge with one I(1)Cs6 pentagonal pyramid, and faces with two equivalent I(2)Cs5Li octahedra. The corner-sharing octahedral tilt angles range from 44-52°. In the third I site, I(3) is bonded in a 4-coordinate geometry to two equivalent Cs(3) and two equivalent Li(1) atoms.
Cs3LiI4 crystallizes in the monoclinic P2_1/m space group. There are three inequivalent Cs sites. In the first Cs site, Cs(1) is bonded to two equivalent I(1) and four equivalent I(2) atoms to form distorted CsI6 pentagonal pyramids that share corners with four equivalent Cs(3)I6 octahedra, corners with four equivalent Li(1)I4 tetrahedra, edges with two equivalent Cs(3)I6 octahedra, and faces with two equivalent Cs(1)I6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 40°. There is one shorter (3.85 Å) and one longer (3.87 Å) Cs(1)-I(1) bond length. All Cs(1)-I(2) bond lengths are 3.90 Å. In the second Cs site, Cs(2) is bonded in a 6-coordinate geometry to six equivalent I(2) atoms. There are a spread of Cs(2)-I(2) bond distances ranging from 3.81-3.92 Å. In the third Cs site, Cs(3) is bonded to two equivalent I(3) and four equivalent I(1) atoms to form CsI6 octahedra that share corners with four equivalent Cs(3)I6 octahedra, corners with four equivalent Cs(1)I6 pentagonal pyramids, corners with four equivalent Li(1)I4 tetrahedra, edges with two equivalent Cs(3)I6 octahedra, edges with two equivalent Cs(1)I6 pentagonal pyramids, and faces with two equivalent Cs(3)I6 octahedra. The corner-sharing octahedral tilt angles are 50°. Both Cs(3)-I(3) bond lengths are 3.96 Å. All Cs(3)-I(1) bond lengths are 3.83 Å. Li(1) is bonded to two equivalent I(2) and two equivalent I(3) atoms to form LiI4 tetrahedra that share corners with four equivalent Cs(3)I6 octahedra, corners with four equivalent Cs(1)I6 pentagonal pyramids, and corners with two equivalent Li(1)I4 tetrahedra. The corner-sharing octahedral tilt angles are 70°. Both Li(1)-I(2) bond lengths are 2.85 Å. There is one shorter (2.87 Å) and one longer (2.88 Å) Li(1)-I(3) bond length. There are three inequivalent I sites. In the first I site, I(1) is bonded to two equivalent Cs(1) and four equivalent Cs(3) atoms to form distorted ICs6 pentagonal pyramids that share corners with four equivalent I(2)Cs5Li octahedra, corners with four equivalent I(1)Cs6 pentagonal pyramids, edges with two equivalent I(2)Cs5Li octahedra, edges with two equivalent I(1)Cs6 pentagonal pyramids, and faces with two equivalent I(1)Cs6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 39°. In the second I site, I(2) is bonded to two equivalent Cs(1), three equivalent Cs(2), and one Li(1) atom to form distorted ICs5Li octahedra that share corners with eight equivalent I(2)Cs5Li octahedra, corners with two equivalent I(1)Cs6 pentagonal pyramids, edges with four equivalent I(2)Cs5Li octahedra,  an edgeedge with one I(1)Cs6 pentagonal pyramid, and faces with two equivalent I(2)Cs5Li octahedra. The corner-sharing octahedral tilt angles range from 44-52°. In the third I site, I(3) is bonded in a 4-coordinate geometry to two equivalent Cs(3) and two equivalent Li(1) atoms.