Ba2Mg(BiO3)2 crystallizes in the monoclinic C2/m space group. Ba(1) is bonded in a 5-coordinate geometry to one O(2) and four equivalent O(1) atoms. Mg(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form MgO6 octahedra that share faces with two equivalent Bi(2)O6 octahedra. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded in a square co-planar geometry to four equivalent O(1) atoms. In the second Bi site, Bi(2) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form distorted BiO6 octahedra that share faces with two equivalent Mg(1)O6 octahedra. There are two inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Ba(1), one Mg(1), one Bi(1), and one Bi(2) atom to form a mixture of distorted corner, edge, and face-sharing OBa2MgBi2 trigonal bipyramids. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one Ba(1), one Mg(1), and one Bi(2) atom.
Ba2Mg(BiO3)2 crystallizes in the monoclinic C2/m space group. Ba(1) is bonded in a 5-coordinate geometry to one O(2) and four equivalent O(1) atoms. The Ba(1)-O(2) bond length is 2.51 Å. There are two shorter (2.79 Å) and two longer (2.81 Å) Ba(1)-O(1) bond lengths. Mg(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form MgO6 octahedra that share faces with two equivalent Bi(2)O6 octahedra. Both Mg(1)-O(2) bond lengths are 2.17 Å. All Mg(1)-O(1) bond lengths are 2.19 Å. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded in a square co-planar geometry to four equivalent O(1) atoms. All Bi(1)-O(1) bond lengths are 2.34 Å. In the second Bi site, Bi(2) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form distorted BiO6 octahedra that share faces with two equivalent Mg(1)O6 octahedra. Both Bi(2)-O(2) bond lengths are 2.24 Å. All Bi(2)-O(1) bond lengths are 2.38 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Ba(1), one Mg(1), one Bi(1), and one Bi(2) atom to form a mixture of distorted corner, edge, and face-sharing OBa2MgBi2 trigonal bipyramids. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one Ba(1), one Mg(1), and one Bi(2) atom.