Sm4OBr6 crystallizes in the hexagonal P6_3mc space group. There are two inequivalent Sm sites. In the first Sm site, Sm(1) is bonded in a distorted single-bond geometry to one O(1), three equivalent Br(1), and four equivalent Br(2) atoms. In the second Sm site, Sm(2) is bonded in a distorted single-bond geometry to one O(1), three equivalent Br(1), and six equivalent Br(2) atoms. O(1) is bonded to one Sm(2) and three equivalent Sm(1) atoms to form OSm4 trigonal pyramids that share corners with six equivalent Br(1)Sm4 tetrahedra and edges with three equivalent Br(1)Sm4 tetrahedra. There are two inequivalent Br sites. In the first Br site, Br(1) is bonded to one Sm(2) and three equivalent Sm(1) atoms to form distorted BrSm4 tetrahedra that share corners with eight equivalent Br(1)Sm4 tetrahedra, corners with two equivalent O(1)Sm4 trigonal pyramids, and  an edgeedge with one O(1)Sm4 trigonal pyramid. In the second Br site, Br(2) is bonded in a 6-coordinate geometry to two equivalent Sm(2) and four equivalent Sm(1) atoms.
Sm4OBr6 crystallizes in the hexagonal P6_3mc space group. There are two inequivalent Sm sites. In the first Sm site, Sm(1) is bonded in a distorted single-bond geometry to one O(1), three equivalent Br(1), and four equivalent Br(2) atoms. The Sm(1)-O(1) bond length is 2.24 Å. There are two shorter (3.01 Å) and one longer (3.13 Å) Sm(1)-Br(1) bond length. There are two shorter (3.06 Å) and two longer (3.49 Å) Sm(1)-Br(2) bond lengths. In the second Sm site, Sm(2) is bonded in a distorted single-bond geometry to one O(1), three equivalent Br(1), and six equivalent Br(2) atoms. The Sm(2)-O(1) bond length is 2.39 Å. All Sm(2)-Br(1) bond lengths are 3.25 Å. There are three shorter (3.16 Å) and three longer (3.86 Å) Sm(2)-Br(2) bond lengths. O(1) is bonded to one Sm(2) and three equivalent Sm(1) atoms to form OSm4 trigonal pyramids that share corners with six equivalent Br(1)Sm4 tetrahedra and edges with three equivalent Br(1)Sm4 tetrahedra. There are two inequivalent Br sites. In the first Br site, Br(1) is bonded to one Sm(2) and three equivalent Sm(1) atoms to form distorted BrSm4 tetrahedra that share corners with eight equivalent Br(1)Sm4 tetrahedra, corners with two equivalent O(1)Sm4 trigonal pyramids, and  an edgeedge with one O(1)Sm4 trigonal pyramid. In the second Br site, Br(2) is bonded in a 6-coordinate geometry to two equivalent Sm(2) and four equivalent Sm(1) atoms.