Ba5MgBi3O11 crystallizes in the monoclinic Cm space group. There are three inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 4-coordinate geometry to one O(2), one O(5), one O(6), and one O(7) atom. In the second Ba site, Ba(2) is bonded in a 6-coordinate geometry to one O(6), one O(7), one O(8), one O(9), and two equivalent O(2) atoms. In the third Ba site, Ba(3) is bonded in a 5-coordinate geometry to one O(3), one O(4), one O(9), and two equivalent O(7) atoms. Mg(1) is bonded in a rectangular see-saw-like geometry to one O(1), one O(3), one O(4), and one O(5) atom. There are three inequivalent Bi sites. In the first Bi site, Bi(1) is bonded to one O(1), one O(3), one O(6), one O(9), and two equivalent O(2) atoms to form corner-sharing BiO6 octahedra. The corner-sharing octahedral tilt angles range from 3-30°. In the second Bi site, Bi(2) is bonded to one O(1), one O(5), one O(6), one O(8), and two equivalent O(2) atoms to form BiO6 octahedra that share corners with four equivalent Bi(1)O6 octahedra and corners with two equivalent Bi(3)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 3-30°. In the third Bi site, Bi(3) is bonded to one O(4), one O(5), one O(8), and two equivalent O(7) atoms to form corner-sharing BiO5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 4-7°. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Mg(1), one Bi(1), and one Bi(2) atom. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Ba(1), two equivalent Ba(2), one Bi(1), and one Bi(2) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Ba(3), one Mg(1), and one Bi(1) atom. In the fourth O site, O(4) is bonded in a distorted T-shaped geometry to one Ba(3), one Mg(1), and one Bi(3) atom. In the fifth O site, O(5) is bonded to two equivalent Ba(1), one Mg(1), one Bi(2), and one Bi(3) atom to form distorted edge-sharing OBa2MgBi2 trigonal bipyramids. In the sixth O site, O(6) is bonded in a 6-coordinate geometry to two equivalent Ba(1), two equivalent Ba(2), one Bi(1), and one Bi(2) atom. In the seventh O site, O(7) is bonded to one Ba(1), one Ba(2), one Ba(3), and one Bi(3) atom to form distorted OBa3Bi trigonal pyramids that share  an edgeedge with one O(5)Ba2MgBi2 trigonal bipyramid and  an edgeedge with one O(7)Ba3Bi trigonal pyramid. In the eighth O site, O(8) is bonded in a rectangular see-saw-like geometry to two equivalent Ba(2), one Bi(2), and one Bi(3) atom. In the ninth O site, O(9) is bonded in a distorted see-saw-like geometry to one Ba(3), two equivalent Ba(2), and one Bi(1) atom.
Ba5MgBi3O11 crystallizes in the monoclinic Cm space group. There are three inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 4-coordinate geometry to one O(2), one O(5), one O(6), and one O(7) atom. The Ba(1)-O(2) bond length is 2.79 Å. The Ba(1)-O(5) bond length is 2.68 Å. The Ba(1)-O(6) bond length is 2.61 Å. The Ba(1)-O(7) bond length is 2.72 Å. In the second Ba site, Ba(2) is bonded in a 6-coordinate geometry to one O(6), one O(7), one O(8), one O(9), and two equivalent O(2) atoms. The Ba(2)-O(6) bond length is 3.18 Å. The Ba(2)-O(7) bond length is 2.77 Å. The Ba(2)-O(8) bond length is 2.85 Å. The Ba(2)-O(9) bond length is 2.63 Å. There is one shorter (2.99 Å) and one longer (3.00 Å) Ba(2)-O(2) bond length. In the third Ba site, Ba(3) is bonded in a 5-coordinate geometry to one O(3), one O(4), one O(9), and two equivalent O(7) atoms. The Ba(3)-O(3) bond length is 2.53 Å. The Ba(3)-O(4) bond length is 2.60 Å. The Ba(3)-O(9) bond length is 2.52 Å. Both Ba(3)-O(7) bond lengths are 3.07 Å. Mg(1) is bonded in a rectangular see-saw-like geometry to one O(1), one O(3), one O(4), and one O(5) atom. The Mg(1)-O(1) bond length is 2.02 Å. The Mg(1)-O(3) bond length is 2.10 Å. The Mg(1)-O(4) bond length is 1.94 Å. The Mg(1)-O(5) bond length is 2.04 Å. There are three inequivalent Bi sites. In the first Bi site, Bi(1) is bonded to one O(1), one O(3), one O(6), one O(9), and two equivalent O(2) atoms to form corner-sharing BiO6 octahedra. The corner-sharing octahedral tilt angles range from 3-30°. The Bi(1)-O(1) bond length is 2.30 Å. The Bi(1)-O(3) bond length is 2.32 Å. The Bi(1)-O(6) bond length is 2.28 Å. The Bi(1)-O(9) bond length is 2.36 Å. Both Bi(1)-O(2) bond lengths are 2.47 Å. In the second Bi site, Bi(2) is bonded to one O(1), one O(5), one O(6), one O(8), and two equivalent O(2) atoms to form BiO6 octahedra that share corners with four equivalent Bi(1)O6 octahedra and corners with two equivalent Bi(3)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 3-30°. The Bi(2)-O(1) bond length is 2.18 Å. The Bi(2)-O(5) bond length is 2.53 Å. The Bi(2)-O(6) bond length is 2.33 Å. The Bi(2)-O(8) bond length is 2.28 Å. Both Bi(2)-O(2) bond lengths are 2.40 Å. In the third Bi site, Bi(3) is bonded to one O(4), one O(5), one O(8), and two equivalent O(7) atoms to form corner-sharing BiO5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 4-7°. The Bi(3)-O(4) bond length is 2.28 Å. The Bi(3)-O(5) bond length is 2.47 Å. The Bi(3)-O(8) bond length is 2.28 Å. Both Bi(3)-O(7) bond lengths are 2.20 Å. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Mg(1), one Bi(1), and one Bi(2) atom. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Ba(1), two equivalent Ba(2), one Bi(1), and one Bi(2) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Ba(3), one Mg(1), and one Bi(1) atom. In the fourth O site, O(4) is bonded in a distorted T-shaped geometry to one Ba(3), one Mg(1), and one Bi(3) atom. In the fifth O site, O(5) is bonded to two equivalent Ba(1), one Mg(1), one Bi(2), and one Bi(3) atom to form distorted edge-sharing OBa2MgBi2 trigonal bipyramids. In the sixth O site, O(6) is bonded in a 6-coordinate geometry to two equivalent Ba(1), two equivalent Ba(2), one Bi(1), and one Bi(2) atom. In the seventh O site, O(7) is bonded to one Ba(1), one Ba(2), one Ba(3), and one Bi(3) atom to form distorted OBa3Bi trigonal pyramids that share  an edgeedge with one O(5)Ba2MgBi2 trigonal bipyramid and  an edgeedge with one O(7)Ba3Bi trigonal pyramid. In the eighth O site, O(8) is bonded in a rectangular see-saw-like geometry to two equivalent Ba(2), one Bi(2), and one Bi(3) atom. In the ninth O site, O(9) is bonded in a distorted see-saw-like geometry to one Ba(3), two equivalent Ba(2), and one Bi(1) atom.