Ba5(OsO5)3Cl crystallizes in the hexagonal P6_3cm space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 11-coordinate geometry to two equivalent O(2), three equivalent O(3), four equivalent O(1), and two equivalent Cl(1) atoms. In the second Ba site, Ba(2) is bonded in a 9-coordinate geometry to three equivalent O(1) and six equivalent O(2) atoms. Os(1) is bonded in a distorted trigonal bipyramidal geometry to one O(3), two equivalent O(1), and two equivalent O(2) atoms. There are three inequivalent O sites. In the first O site, O(1) is bonded to one Ba(2), two equivalent Ba(1), and one Os(1) atom to form distorted OBa3Os tetrahedra that share corners with two equivalent Cl(1)Ba6 octahedra, corners with six equivalent O(2)Ba3Os tetrahedra, corners with seven equivalent O(1)Ba3Os tetrahedra,  an edgeedge with one Cl(1)Ba6 octahedra,  an edgeedge with one O(1)Ba3Os tetrahedra, and edges with three equivalent O(2)Ba3Os tetrahedra. The corner-sharing octahedral tilt angles range from 49-72°. In the second O site, O(2) is bonded to one Ba(1), two equivalent Ba(2), and one Os(1) atom to form distorted OBa3Os tetrahedra that share corners with two equivalent Cl(1)Ba6 octahedra, corners with six equivalent O(1)Ba3Os tetrahedra, corners with six equivalent O(2)Ba3Os tetrahedra, edges with three equivalent O(1)Ba3Os tetrahedra, and edges with three equivalent O(2)Ba3Os tetrahedra. The corner-sharing octahedral tilt angles range from 41-43°. In the third O site, O(3) is bonded in a distorted single-bond geometry to three equivalent Ba(1) and one Os(1) atom. Cl(1) is bonded to six equivalent Ba(1) atoms to form ClBa6 octahedra that share corners with twelve equivalent O(1)Ba3Os tetrahedra, corners with twelve equivalent O(2)Ba3Os tetrahedra, edges with six equivalent O(1)Ba3Os tetrahedra, and faces with two equivalent Cl(1)Ba6 octahedra.
Ba5(OsO5)3Cl crystallizes in the hexagonal P6_3cm space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 11-coordinate geometry to two equivalent O(2), three equivalent O(3), four equivalent O(1), and two equivalent Cl(1) atoms. Both Ba(1)-O(2) bond lengths are 2.79 Å. There is one shorter (3.03 Å) and two longer (3.27 Å) Ba(1)-O(3) bond lengths. There are two shorter (2.79 Å) and two longer (2.94 Å) Ba(1)-O(1) bond lengths. There is one shorter (3.46 Å) and one longer (3.65 Å) Ba(1)-Cl(1) bond length. In the second Ba site, Ba(2) is bonded in a 9-coordinate geometry to three equivalent O(1) and six equivalent O(2) atoms. All Ba(2)-O(1) bond lengths are 2.82 Å. There are three shorter (2.76 Å) and three longer (2.83 Å) Ba(2)-O(2) bond lengths. Os(1) is bonded in a distorted trigonal bipyramidal geometry to one O(3), two equivalent O(1), and two equivalent O(2) atoms. The Os(1)-O(3) bond length is 1.75 Å. Both Os(1)-O(1) bond lengths are 1.87 Å. Both Os(1)-O(2) bond lengths are 1.87 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded to one Ba(2), two equivalent Ba(1), and one Os(1) atom to form distorted OBa3Os tetrahedra that share corners with two equivalent Cl(1)Ba6 octahedra, corners with six equivalent O(2)Ba3Os tetrahedra, corners with seven equivalent O(1)Ba3Os tetrahedra,  an edgeedge with one Cl(1)Ba6 octahedra,  an edgeedge with one O(1)Ba3Os tetrahedra, and edges with three equivalent O(2)Ba3Os tetrahedra. The corner-sharing octahedral tilt angles range from 49-72°. In the second O site, O(2) is bonded to one Ba(1), two equivalent Ba(2), and one Os(1) atom to form distorted OBa3Os tetrahedra that share corners with two equivalent Cl(1)Ba6 octahedra, corners with six equivalent O(1)Ba3Os tetrahedra, corners with six equivalent O(2)Ba3Os tetrahedra, edges with three equivalent O(1)Ba3Os tetrahedra, and edges with three equivalent O(2)Ba3Os tetrahedra. The corner-sharing octahedral tilt angles range from 41-43°. In the third O site, O(3) is bonded in a distorted single-bond geometry to three equivalent Ba(1) and one Os(1) atom. Cl(1) is bonded to six equivalent Ba(1) atoms to form ClBa6 octahedra that share corners with twelve equivalent O(1)Ba3Os tetrahedra, corners with twelve equivalent O(2)Ba3Os tetrahedra, edges with six equivalent O(1)Ba3Os tetrahedra, and faces with two equivalent Cl(1)Ba6 octahedra.