LiSm2Br5 crystallizes in the monoclinic C2/c space group. Li(1) is bonded to two equivalent Br(3) and four equivalent Br(2) atoms to form corner-sharing LiBr6 octahedra. The corner-sharing octahedral tilt angles are 43°. Sm(1) is bonded in a 7-coordinate geometry to two equivalent Br(1), two equivalent Br(2), and three equivalent Br(3) atoms. There are three inequivalent Br sites. In the first Br site, Br(1) is bonded to four equivalent Sm(1) atoms to form distorted BrSm4 trigonal pyramids that share corners with eight equivalent Br(3)LiSm3 tetrahedra, edges with two equivalent Br(3)LiSm3 tetrahedra, and edges with two equivalent Br(1)Sm4 trigonal pyramids. In the second Br site, Br(2) is bonded in a 4-coordinate geometry to two equivalent Li(1) and two equivalent Sm(1) atoms. In the third Br site, Br(3) is bonded to one Li(1) and three equivalent Sm(1) atoms to form distorted BrLiSm3 tetrahedra that share corners with three equivalent Br(3)LiSm3 tetrahedra, corners with four equivalent Br(1)Sm4 trigonal pyramids, edges with two equivalent Br(3)LiSm3 tetrahedra, and  an edgeedge with one Br(1)Sm4 trigonal pyramid.
LiSm2Br5 crystallizes in the monoclinic C2/c space group. Li(1) is bonded to two equivalent Br(3) and four equivalent Br(2) atoms to form corner-sharing LiBr6 octahedra. The corner-sharing octahedral tilt angles are 43°. Both Li(1)-Br(3) bond lengths are 2.86 Å. There are two shorter (2.55 Å) and two longer (3.10 Å) Li(1)-Br(2) bond lengths. Sm(1) is bonded in a 7-coordinate geometry to two equivalent Br(1), two equivalent Br(2), and three equivalent Br(3) atoms. There is one shorter (2.81 Å) and one longer (2.89 Å) Sm(1)-Br(1) bond length. There is one shorter (3.08 Å) and one longer (3.35 Å) Sm(1)-Br(2) bond length. There are a spread of Sm(1)-Br(3) bond distances ranging from 3.02-3.16 Å. There are three inequivalent Br sites. In the first Br site, Br(1) is bonded to four equivalent Sm(1) atoms to form distorted BrSm4 trigonal pyramids that share corners with eight equivalent Br(3)LiSm3 tetrahedra, edges with two equivalent Br(3)LiSm3 tetrahedra, and edges with two equivalent Br(1)Sm4 trigonal pyramids. In the second Br site, Br(2) is bonded in a 4-coordinate geometry to two equivalent Li(1) and two equivalent Sm(1) atoms. In the third Br site, Br(3) is bonded to one Li(1) and three equivalent Sm(1) atoms to form distorted BrLiSm3 tetrahedra that share corners with three equivalent Br(3)LiSm3 tetrahedra, corners with four equivalent Br(1)Sm4 trigonal pyramids, edges with two equivalent Br(3)LiSm3 tetrahedra, and  an edgeedge with one Br(1)Sm4 trigonal pyramid.