Eu2CuO4 crystallizes in the tetragonal I4/mmm space group. Eu(1) is bonded in a body-centered cubic geometry to four equivalent O(1) and four equivalent O(2) atoms. Cu(1) is bonded in a square co-planar geometry to four equivalent O(2) atoms. There are two inequivalent O sites. In the first O site, O(2) is bonded to four equivalent Eu(1) and two equivalent Cu(1) atoms to form distorted OEu4Cu2 octahedra that share corners with two equivalent O(2)Eu4Cu2 octahedra, corners with twelve equivalent O(1)Eu4 tetrahedra, edges with two equivalent O(2)Eu4Cu2 octahedra, edges with two equivalent O(1)Eu4 tetrahedra, and faces with four equivalent O(2)Eu4Cu2 octahedra. The corner-sharing octahedra are not tilted. In the second O site, O(1) is bonded to four equivalent Eu(1) atoms to form OEu4 tetrahedra that share corners with twelve equivalent O(2)Eu4Cu2 octahedra, corners with four equivalent O(1)Eu4 tetrahedra, edges with two equivalent O(2)Eu4Cu2 octahedra, and edges with four equivalent O(1)Eu4 tetrahedra. The corner-sharing octahedral tilt angles range from 10-69°.
Eu2CuO4 crystallizes in the tetragonal I4/mmm space group. Eu(1) is bonded in a body-centered cubic geometry to four equivalent O(1) and four equivalent O(2) atoms. All Eu(1)-O(1) bond lengths are 2.30 Å. All Eu(1)-O(2) bond lengths are 2.63 Å. Cu(1) is bonded in a square co-planar geometry to four equivalent O(2) atoms. All Cu(1)-O(2) bond lengths are 1.94 Å. There are two inequivalent O sites. In the first O site, O(2) is bonded to four equivalent Eu(1) and two equivalent Cu(1) atoms to form distorted OEu4Cu2 octahedra that share corners with two equivalent O(2)Eu4Cu2 octahedra, corners with twelve equivalent O(1)Eu4 tetrahedra, edges with two equivalent O(2)Eu4Cu2 octahedra, edges with two equivalent O(1)Eu4 tetrahedra, and faces with four equivalent O(2)Eu4Cu2 octahedra. The corner-sharing octahedra are not tilted. In the second O site, O(1) is bonded to four equivalent Eu(1) atoms to form OEu4 tetrahedra that share corners with twelve equivalent O(2)Eu4Cu2 octahedra, corners with four equivalent O(1)Eu4 tetrahedra, edges with two equivalent O(2)Eu4Cu2 octahedra, and edges with four equivalent O(1)Eu4 tetrahedra. The corner-sharing octahedral tilt angles range from 10-69°.