Ba2CuO4 crystallizes in the tetragonal I4/mmm space group. Ba(1) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(2), and four equivalent O(3) atoms. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a square co-planar geometry to four equivalent O(3) atoms. In the second Cu site, Cu(2) is bonded in a square co-planar geometry to four equivalent O(3) atoms. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to four equivalent Ba(1) and one O(2) atom. In the second O site, O(2) is bonded in a 5-coordinate geometry to four equivalent Ba(1) and one O(1) atom. In the third O site, O(3) is bonded to four equivalent Ba(1), one Cu(1), and one Cu(2) atom to form a mixture of distorted corner, edge, and face-sharing OBa4Cu2 octahedra. The corner-sharing octahedra are not tilted.
Ba2CuO4 crystallizes in the tetragonal I4/mmm space group. Ba(1) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(2), and four equivalent O(3) atoms. Both Ba(1)-O(1) bond lengths are 2.98 Å. Both Ba(1)-O(2) bond lengths are 2.92 Å. All Ba(1)-O(3) bond lengths are 2.75 Å. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a square co-planar geometry to four equivalent O(3) atoms. All Cu(1)-O(3) bond lengths are 1.95 Å. In the second Cu site, Cu(2) is bonded in a square co-planar geometry to four equivalent O(3) atoms. All Cu(2)-O(3) bond lengths are 1.94 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to four equivalent Ba(1) and one O(2) atom. The O(1)-O(2) bond length is 1.54 Å. In the second O site, O(2) is bonded in a 5-coordinate geometry to four equivalent Ba(1) and one O(1) atom. In the third O site, O(3) is bonded to four equivalent Ba(1), one Cu(1), and one Cu(2) atom to form a mixture of distorted corner, edge, and face-sharing OBa4Cu2 octahedra. The corner-sharing octahedra are not tilted.