Mg(CuO)2 crystallizes in the monoclinic C2 space group. Mg(1) is bonded in a square co-planar geometry to four equivalent O(1) atoms. Cu(1) is bonded in a distorted trigonal planar geometry to one 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 Mg(1) and two equivalent Cu(1) atoms to form OMg4Cu2 octahedra that share corners with four equivalent O(1)Mg4Cu2 octahedra, corners with four equivalent O(2)Cu4 tetrahedra, and edges with four equivalent O(1)Mg4Cu2 octahedra. The corner-sharing octahedra are not tilted. In the second O site, O(2) is bonded to four equivalent Cu(1) atoms to form OCu4 tetrahedra that share corners with four equivalent O(1)Mg4Cu2 octahedra and corners with four equivalent O(2)Cu4 tetrahedra. The corner-sharing octahedral tilt angles range from 49-50°.
Mg(CuO)2 crystallizes in the monoclinic C2 space group. Mg(1) is bonded in a square co-planar geometry to four equivalent O(1) atoms. All Mg(1)-O(1) bond lengths are 2.08 Å. Cu(1) is bonded in a distorted trigonal planar geometry to one O(1) and two equivalent O(2) atoms. The Cu(1)-O(1) bond length is 2.20 Å. Both Cu(1)-O(2) bond lengths are 1.94 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Mg(1) and two equivalent Cu(1) atoms to form OMg4Cu2 octahedra that share corners with four equivalent O(1)Mg4Cu2 octahedra, corners with four equivalent O(2)Cu4 tetrahedra, and edges with four equivalent O(1)Mg4Cu2 octahedra. The corner-sharing octahedra are not tilted. In the second O site, O(2) is bonded to four equivalent Cu(1) atoms to form OCu4 tetrahedra that share corners with four equivalent O(1)Mg4Cu2 octahedra and corners with four equivalent O(2)Cu4 tetrahedra. The corner-sharing octahedral tilt angles range from 49-50°.