Ba8Mn8O23 crystallizes in the orthorhombic Amm2 space group. There are five inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 11-coordinate geometry to one O(3), two equivalent O(2), two equivalent O(4), two equivalent O(6), and four equivalent O(9) atoms. In the second Ba site, Ba(2) is bonded to one O(3), one O(7), two equivalent O(1), two equivalent O(2), two equivalent O(5), and four equivalent O(8) atoms to form distorted BaO12 cuboctahedra that share corners with six equivalent Ba(2)O12 cuboctahedra, corners with three equivalent Mn(2)O6 octahedra, corners with three equivalent Mn(3)O6 octahedra,  a faceface with one Ba(2)O12 cuboctahedra, faces with three equivalent Ba(4)O12 cuboctahedra, faces with three equivalent Ba(5)O12 cuboctahedra, faces with three equivalent Mn(1)O6 octahedra, and faces with three equivalent Mn(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 11-12°. In the third Ba site, Ba(3) is bonded in a 10-coordinate geometry to two equivalent O(6), four equivalent O(4), and four equivalent O(9) atoms. In the fourth Ba site, Ba(4) is bonded to one O(5), one O(6), two equivalent O(3), two equivalent O(8), two equivalent O(9), and four equivalent O(2) atoms to form distorted BaO12 cuboctahedra that share corners with six equivalent Ba(4)O12 cuboctahedra, corners with three equivalent Mn(3)O6 octahedra,  a faceface with one Ba(5)O12 cuboctahedra, faces with three equivalent Ba(2)O12 cuboctahedra, faces with three equivalent Mn(1)O6 octahedra, faces with three equivalent Mn(2)O6 octahedra, and  a faceface with one Mn(4)O5 square pyramid. The corner-sharing octahedral tilt angles range from 10-12°. In the fifth Ba site, Ba(5) is bonded to two equivalent O(5), two equivalent O(7), four equivalent O(1), and four equivalent O(8) atoms to form BaO12 cuboctahedra that share corners with six equivalent Ba(5)O12 cuboctahedra, corners with six equivalent Mn(1)O6 octahedra, faces with two equivalent Ba(4)O12 cuboctahedra, faces with six equivalent Ba(2)O12 cuboctahedra, and faces with six equivalent Mn(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 12-13°. There are four inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one O(3), one O(5), two equivalent O(2), and two equivalent O(8) atoms to form MnO6 octahedra that share corners with three equivalent Ba(5)O12 cuboctahedra, faces with three equivalent Ba(2)O12 cuboctahedra, faces with three equivalent Ba(4)O12 cuboctahedra,  a faceface with one Mn(2)O6 octahedra, and  a faceface with one Mn(3)O6 octahedra. In the second Mn site, Mn(2) is bonded to one O(3), one O(6), two equivalent O(2), and two equivalent O(9) atoms to form MnO6 octahedra that share corners with three equivalent Ba(2)O12 cuboctahedra, corners with three equivalent Mn(4)O5 square pyramids, faces with three equivalent Ba(4)O12 cuboctahedra, and  a faceface with one Mn(1)O6 octahedra. In the third Mn site, Mn(3) is bonded to one O(5), one O(7), two equivalent O(1), and two equivalent O(8) atoms to form MnO6 octahedra that share corners with three equivalent Ba(2)O12 cuboctahedra, corners with three equivalent Ba(4)O12 cuboctahedra, faces with three equivalent Ba(2)O12 cuboctahedra, faces with three equivalent Ba(5)O12 cuboctahedra,  a faceface with one Mn(1)O6 octahedra, and  a faceface with one Mn(3)O6 octahedra. In the fourth Mn site, Mn(4) is bonded to one O(6), two equivalent O(4), and two equivalent O(9) atoms to form MnO5 square pyramids that share corners with three equivalent Mn(2)O6 octahedra,  an edgeedge with one Mn(4)O5 square pyramid, and  a faceface with one Ba(4)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 1-5°. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a 2-coordinate geometry to two equivalent Ba(2), two equivalent Ba(5), and two equivalent Mn(3) atoms. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Ba(1), one Ba(2), two equivalent Ba(4), one Mn(1), and one Mn(2) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to one Ba(1), one Ba(2), two equivalent Ba(4), one Mn(1), and one Mn(2) atom. In the fourth O site, O(4) is bonded in a distorted L-shaped geometry to two equivalent Ba(1), two equivalent Ba(3), and two equivalent Mn(4) atoms. In the fifth O site, O(5) is bonded in a 2-coordinate geometry to one Ba(4), one Ba(5), two equivalent Ba(2), one Mn(1), and one Mn(3) atom. In the sixth O site, O(6) is bonded in a distorted linear geometry to one Ba(3), one Ba(4), two equivalent Ba(1), one Mn(2), and one Mn(4) atom. In the seventh O site, O(7) is bonded in a 2-coordinate geometry to two equivalent Ba(2), two equivalent Ba(5), and two equivalent Mn(3) atoms. In the eighth O site, O(8) is bonded in a 2-coordinate geometry to one Ba(4), one Ba(5), two equivalent Ba(2), one Mn(1), and one Mn(3) atom. In the ninth O site, O(9) is bonded in a distorted linear geometry to one Ba(3), one Ba(4), two equivalent Ba(1), one Mn(2), and one Mn(4) atom.
Ba8Mn8O23 crystallizes in the orthorhombic Amm2 space group. There are five inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 11-coordinate geometry to one O(3), two equivalent O(2), two equivalent O(4), two equivalent O(6), and four equivalent O(9) atoms. The Ba(1)-O(3) bond length is 2.73 Å. Both Ba(1)-O(2) bond lengths are 2.78 Å. Both Ba(1)-O(4) bond lengths are 3.26 Å. Both Ba(1)-O(6) bond lengths are 2.86 Å. There are two shorter (2.86 Å) and two longer (2.90 Å) Ba(1)-O(9) bond lengths. In the second Ba site, Ba(2) is bonded to one O(3), one O(7), two equivalent O(1), two equivalent O(2), two equivalent O(5), and four equivalent O(8) atoms to form distorted BaO12 cuboctahedra that share corners with six equivalent Ba(2)O12 cuboctahedra, corners with three equivalent Mn(2)O6 octahedra, corners with three equivalent Mn(3)O6 octahedra,  a faceface with one Ba(2)O12 cuboctahedra, faces with three equivalent Ba(4)O12 cuboctahedra, faces with three equivalent Ba(5)O12 cuboctahedra, faces with three equivalent Mn(1)O6 octahedra, and faces with three equivalent Mn(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 11-12°. The Ba(2)-O(3) bond length is 3.09 Å. The Ba(2)-O(7) bond length is 2.99 Å. Both Ba(2)-O(1) bond lengths are 2.98 Å. Both Ba(2)-O(2) bond lengths are 3.14 Å. Both Ba(2)-O(5) bond lengths are 2.86 Å. All Ba(2)-O(8) bond lengths are 2.87 Å. In the third Ba site, Ba(3) is bonded in a 10-coordinate geometry to two equivalent O(6), four equivalent O(4), and four equivalent O(9) atoms. Both Ba(3)-O(6) bond lengths are 2.85 Å. There are two shorter (2.73 Å) and two longer (3.04 Å) Ba(3)-O(4) bond lengths. All Ba(3)-O(9) bond lengths are 2.84 Å. In the fourth Ba site, Ba(4) is bonded to one O(5), one O(6), two equivalent O(3), two equivalent O(8), two equivalent O(9), and four equivalent O(2) atoms to form distorted BaO12 cuboctahedra that share corners with six equivalent Ba(4)O12 cuboctahedra, corners with three equivalent Mn(3)O6 octahedra,  a faceface with one Ba(5)O12 cuboctahedra, faces with three equivalent Ba(2)O12 cuboctahedra, faces with three equivalent Mn(1)O6 octahedra, faces with three equivalent Mn(2)O6 octahedra, and  a faceface with one Mn(4)O5 square pyramid. The corner-sharing octahedral tilt angles range from 10-12°. The Ba(4)-O(5) bond length is 2.89 Å. The Ba(4)-O(6) bond length is 3.03 Å. Both Ba(4)-O(3) bond lengths are 2.86 Å. Both Ba(4)-O(8) bond lengths are 2.90 Å. Both Ba(4)-O(9) bond lengths are 3.05 Å. There are two shorter (2.86 Å) and two longer (2.90 Å) Ba(4)-O(2) bond lengths. In the fifth Ba site, Ba(5) is bonded to two equivalent O(5), two equivalent O(7), four equivalent O(1), and four equivalent O(8) atoms to form BaO12 cuboctahedra that share corners with six equivalent Ba(5)O12 cuboctahedra, corners with six equivalent Mn(1)O6 octahedra, faces with two equivalent Ba(4)O12 cuboctahedra, faces with six equivalent Ba(2)O12 cuboctahedra, and faces with six equivalent Mn(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 12-13°. Both Ba(5)-O(5) bond lengths are 3.07 Å. Both Ba(5)-O(7) bond lengths are 2.86 Å. All Ba(5)-O(1) bond lengths are 2.87 Å. All Ba(5)-O(8) bond lengths are 3.03 Å. There are four inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one O(3), one O(5), two equivalent O(2), and two equivalent O(8) atoms to form MnO6 octahedra that share corners with three equivalent Ba(5)O12 cuboctahedra, faces with three equivalent Ba(2)O12 cuboctahedra, faces with three equivalent Ba(4)O12 cuboctahedra,  a faceface with one Mn(2)O6 octahedra, and  a faceface with one Mn(3)O6 octahedra. The Mn(1)-O(3) bond length is 1.88 Å. The Mn(1)-O(5) bond length is 1.94 Å. Both Mn(1)-O(2) bond lengths are 1.87 Å. Both Mn(1)-O(8) bond lengths are 1.93 Å. In the second Mn site, Mn(2) is bonded to one O(3), one O(6), two equivalent O(2), and two equivalent O(9) atoms to form MnO6 octahedra that share corners with three equivalent Ba(2)O12 cuboctahedra, corners with three equivalent Mn(4)O5 square pyramids, faces with three equivalent Ba(4)O12 cuboctahedra, and  a faceface with one Mn(1)O6 octahedra. The Mn(2)-O(3) bond length is 2.01 Å. The Mn(2)-O(6) bond length is 1.85 Å. Both Mn(2)-O(2) bond lengths are 1.95 Å. Both Mn(2)-O(9) bond lengths are 1.93 Å. In the third Mn site, Mn(3) is bonded to one O(5), one O(7), two equivalent O(1), and two equivalent O(8) atoms to form MnO6 octahedra that share corners with three equivalent Ba(2)O12 cuboctahedra, corners with three equivalent Ba(4)O12 cuboctahedra, faces with three equivalent Ba(2)O12 cuboctahedra, faces with three equivalent Ba(5)O12 cuboctahedra,  a faceface with one Mn(1)O6 octahedra, and  a faceface with one Mn(3)O6 octahedra. The Mn(3)-O(5) bond length is 1.89 Å. The Mn(3)-O(7) bond length is 1.91 Å. Both Mn(3)-O(1) bond lengths are 1.91 Å. Both Mn(3)-O(8) bond lengths are 1.90 Å. In the fourth Mn site, Mn(4) is bonded to one O(6), two equivalent O(4), and two equivalent O(9) atoms to form MnO5 square pyramids that share corners with three equivalent Mn(2)O6 octahedra,  an edgeedge with one Mn(4)O5 square pyramid, and  a faceface with one Ba(4)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 1-5°. The Mn(4)-O(6) bond length is 1.98 Å. Both Mn(4)-O(4) bond lengths are 1.91 Å. Both Mn(4)-O(9) bond lengths are 1.94 Å. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a 2-coordinate geometry to two equivalent Ba(2), two equivalent Ba(5), and two equivalent Mn(3) atoms. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Ba(1), one Ba(2), two equivalent Ba(4), one Mn(1), and one Mn(2) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to one Ba(1), one Ba(2), two equivalent Ba(4), one Mn(1), and one Mn(2) atom. In the fourth O site, O(4) is bonded in a distorted L-shaped geometry to two equivalent Ba(1), two equivalent Ba(3), and two equivalent Mn(4) atoms. In the fifth O site, O(5) is bonded in a 2-coordinate geometry to one Ba(4), one Ba(5), two equivalent Ba(2), one Mn(1), and one Mn(3) atom. In the sixth O site, O(6) is bonded in a distorted linear geometry to one Ba(3), one Ba(4), two equivalent Ba(1), one Mn(2), and one Mn(4) atom. In the seventh O site, O(7) is bonded in a 2-coordinate geometry to two equivalent Ba(2), two equivalent Ba(5), and two equivalent Mn(3) atoms. In the eighth O site, O(8) is bonded in a 2-coordinate geometry to one Ba(4), one Ba(5), two equivalent Ba(2), one Mn(1), and one Mn(3) atom. In the ninth O site, O(9) is bonded in a distorted linear geometry to one Ba(3), one Ba(4), two equivalent Ba(1), one Mn(2), and one Mn(4) atom.