Ba2CuO3 crystallizes in the orthorhombic Immm space group. Ba(1) is bonded to two equivalent O(1) and five equivalent O(2) atoms to form a mixture of distorted corner, edge, and face-sharing BaO7 pentagonal bipyramids. Cu(1) is bonded in a square co-planar geometry to two equivalent O(1) and two equivalent O(2) atoms. There are two inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Ba(1) and two equivalent Cu(1) atoms to form OBa4Cu2 octahedra that share corners with two equivalent O(1)Ba4Cu2 octahedra, corners with twelve equivalent O(2)Ba5Cu octahedra, edges with two equivalent O(1)Ba4Cu2 octahedra, and faces with four equivalent O(2)Ba5Cu octahedra. The corner-sharing octahedral tilt angles range from 0-61°. In the second O site, O(2) is bonded to five equivalent Ba(1) and one Cu(1) atom to form OBa5Cu octahedra that share corners with five equivalent O(2)Ba5Cu octahedra, corners with six equivalent O(1)Ba4Cu2 octahedra, edges with eight equivalent O(2)Ba5Cu octahedra, and faces with two equivalent O(1)Ba4Cu2 octahedra. The corner-sharing octahedral tilt angles range from 0-61°.
Ba2CuO3 crystallizes in the orthorhombic Immm space group. Ba(1) is bonded to two equivalent O(1) and five equivalent O(2) atoms to form a mixture of distorted corner, edge, and face-sharing BaO7 pentagonal bipyramids. Both Ba(1)-O(1) bond lengths are 2.70 Å. There is one shorter (2.73 Å) and four longer (2.82 Å) Ba(1)-O(2) bond lengths. Cu(1) is bonded in a square co-planar geometry to two equivalent O(1) and two equivalent O(2) atoms. Both Cu(1)-O(1) bond lengths are 2.06 Å. Both Cu(1)-O(2) bond lengths are 1.92 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Ba(1) and two equivalent Cu(1) atoms to form OBa4Cu2 octahedra that share corners with two equivalent O(1)Ba4Cu2 octahedra, corners with twelve equivalent O(2)Ba5Cu octahedra, edges with two equivalent O(1)Ba4Cu2 octahedra, and faces with four equivalent O(2)Ba5Cu octahedra. The corner-sharing octahedral tilt angles range from 0-61°. In the second O site, O(2) is bonded to five equivalent Ba(1) and one Cu(1) atom to form OBa5Cu octahedra that share corners with five equivalent O(2)Ba5Cu octahedra, corners with six equivalent O(1)Ba4Cu2 octahedra, edges with eight equivalent O(2)Ba5Cu octahedra, and faces with two equivalent O(1)Ba4Cu2 octahedra. The corner-sharing octahedral tilt angles range from 0-61°.