Mg2Cu2O5 crystallizes in the orthorhombic Pbam space group. Mg(1) is bonded in a 7-coordinate geometry to two equivalent O(1), two equivalent O(2), and three equivalent O(3) atoms. Cu(1) is bonded to one O(1), two equivalent O(2), and two equivalent O(3) atoms to form corner-sharing CuO5 square pyramids. There are three 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 eight equivalent O(2)Mg2Cu2 tetrahedra, corners with four equivalent O(3)Mg3Cu2 trigonal bipyramids, edges with two equivalent O(1)Mg4Cu2 octahedra, edges with two equivalent O(2)Mg2Cu2 tetrahedra, and faces with four equivalent O(3)Mg3Cu2 trigonal bipyramids. In the second O site, O(2) is bonded to two equivalent Mg(1) and two equivalent Cu(1) atoms to form OMg2Cu2 tetrahedra that share corners with four equivalent O(1)Mg4Cu2 octahedra, corners with four equivalent O(2)Mg2Cu2 tetrahedra, corners with six equivalent O(3)Mg3Cu2 trigonal bipyramids,  an edgeedge with one O(1)Mg4Cu2 octahedra, and edges with two equivalent O(3)Mg3Cu2 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 12-59°. In the third O site, O(3) is bonded to three equivalent Mg(1) and two equivalent Cu(1) atoms to form distorted OMg3Cu2 trigonal bipyramids that share corners with two equivalent O(1)Mg4Cu2 octahedra, corners with six equivalent O(2)Mg2Cu2 tetrahedra, corners with four equivalent O(3)Mg3Cu2 trigonal bipyramids, edges with two equivalent O(2)Mg2Cu2 tetrahedra, edges with two equivalent O(3)Mg3Cu2 trigonal bipyramids, and faces with two equivalent O(1)Mg4Cu2 octahedra. The corner-sharing octahedral tilt angles are 64°.
Mg2Cu2O5 crystallizes in the orthorhombic Pbam space group. Mg(1) is bonded in a 7-coordinate geometry to two equivalent O(1), two equivalent O(2), and three equivalent O(3) atoms. Both Mg(1)-O(1) bond lengths are 2.36 Å. Both Mg(1)-O(2) bond lengths are 2.09 Å. There are a spread of Mg(1)-O(3) bond distances ranging from 2.14-2.45 Å. Cu(1) is bonded to one O(1), two equivalent O(2), and two equivalent O(3) atoms to form corner-sharing CuO5 square pyramids. The Cu(1)-O(1) bond length is 1.94 Å. There is one shorter (1.91 Å) and one longer (2.04 Å) Cu(1)-O(2) bond length. Both Cu(1)-O(3) bond lengths are 1.90 Å. There are three 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 eight equivalent O(2)Mg2Cu2 tetrahedra, corners with four equivalent O(3)Mg3Cu2 trigonal bipyramids, edges with two equivalent O(1)Mg4Cu2 octahedra, edges with two equivalent O(2)Mg2Cu2 tetrahedra, and faces with four equivalent O(3)Mg3Cu2 trigonal bipyramids. In the second O site, O(2) is bonded to two equivalent Mg(1) and two equivalent Cu(1) atoms to form OMg2Cu2 tetrahedra that share corners with four equivalent O(1)Mg4Cu2 octahedra, corners with four equivalent O(2)Mg2Cu2 tetrahedra, corners with six equivalent O(3)Mg3Cu2 trigonal bipyramids,  an edgeedge with one O(1)Mg4Cu2 octahedra, and edges with two equivalent O(3)Mg3Cu2 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 12-59°. In the third O site, O(3) is bonded to three equivalent Mg(1) and two equivalent Cu(1) atoms to form distorted OMg3Cu2 trigonal bipyramids that share corners with two equivalent O(1)Mg4Cu2 octahedra, corners with six equivalent O(2)Mg2Cu2 tetrahedra, corners with four equivalent O(3)Mg3Cu2 trigonal bipyramids, edges with two equivalent O(2)Mg2Cu2 tetrahedra, edges with two equivalent O(3)Mg3Cu2 trigonal bipyramids, and faces with two equivalent O(1)Mg4Cu2 octahedra. The corner-sharing octahedral tilt angles are 64°.