Ba2MgCuO3 crystallizes in the orthorhombic Imm2 space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 6-coordinate geometry to two equivalent O(1) and four equivalent O(3) atoms. In the second Ba site, Ba(2) is bonded in a 6-coordinate geometry to two equivalent O(1) and four equivalent O(2) atoms. Mg(1) is bonded to two equivalent O(2) and two equivalent O(3) atoms to form corner-sharing MgO4 tetrahedra. Cu(1) is bonded in a linear geometry to two equivalent O(1) atoms. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Ba(1), two equivalent Ba(2), and two equivalent Cu(1) atoms to form a mixture of distorted corner and edge-sharing OBa4Cu2 octahedra. The corner-sharing octahedral tilt angles are 1°. In the second O site, O(2) is bonded in a distorted bent 120 degrees geometry to four equivalent Ba(2) and two equivalent Mg(1) atoms. In the third O site, O(3) is bonded in a distorted bent 120 degrees geometry to four equivalent Ba(1) and two equivalent Mg(1) atoms.
Ba2MgCuO3 crystallizes in the orthorhombic Imm2 space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 6-coordinate geometry to two equivalent O(1) and four equivalent O(3) atoms. Both Ba(1)-O(1) bond lengths are 2.73 Å. All Ba(1)-O(3) bond lengths are 2.98 Å. In the second Ba site, Ba(2) is bonded in a 6-coordinate geometry to two equivalent O(1) and four equivalent O(2) atoms. Both Ba(2)-O(1) bond lengths are 2.76 Å. All Ba(2)-O(2) bond lengths are 2.98 Å. Mg(1) is bonded to two equivalent O(2) and two equivalent O(3) atoms to form corner-sharing MgO4 tetrahedra. Both Mg(1)-O(2) bond lengths are 2.10 Å. Both Mg(1)-O(3) bond lengths are 2.18 Å. Cu(1) is bonded in a linear geometry to two equivalent O(1) atoms. Both Cu(1)-O(1) bond lengths are 1.86 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Ba(1), two equivalent Ba(2), and two equivalent Cu(1) atoms to form a mixture of distorted corner and edge-sharing OBa4Cu2 octahedra. The corner-sharing octahedral tilt angles are 1°. In the second O site, O(2) is bonded in a distorted bent 120 degrees geometry to four equivalent Ba(2) and two equivalent Mg(1) atoms. In the third O site, O(3) is bonded in a distorted bent 120 degrees geometry to four equivalent Ba(1) and two equivalent Mg(1) atoms.