MgNd4(Cu2O5)2 crystallizes in the monoclinic Pm space group. Mg(1) is bonded in a 6-coordinate geometry to one O(7), one O(8), two equivalent O(3), and two equivalent O(4) atoms. There are four inequivalent Nd sites. In the first Nd site, Nd(1) is bonded in a 9-coordinate geometry to one O(10), one O(7), one O(9), two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms. In the second Nd site, Nd(2) is bonded in a 7-coordinate geometry to one O(10), one O(8), one O(9), two equivalent O(2), and two equivalent O(6) atoms. In the third Nd site, Nd(3) is bonded in a 8-coordinate geometry to one O(10), one O(7), two equivalent O(1), two equivalent O(3), and two equivalent O(5) atoms. In the fourth Nd site, Nd(4) is bonded in a 9-coordinate geometry to one O(7), one O(8), one O(9), two equivalent O(1), two equivalent O(4), and two equivalent O(6) atoms. There are four inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to one O(1), one O(3), one O(4), one O(5), and two equivalent O(7) atoms to form distorted CuO6 octahedra that share corners with two equivalent Cu(1)O6 octahedra and corners with two equivalent Cu(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 6°. In the second Cu site, Cu(2) is bonded to one O(1), one O(4), one O(6), and two equivalent O(8) atoms to form distorted CuO5 trigonal bipyramids that share corners with two equivalent Cu(1)O6 octahedra and corners with two equivalent Cu(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 9-73°. In the third Cu site, Cu(3) is bonded in a 3-coordinate geometry to one O(2), one O(5), one O(6), and two equivalent O(10) atoms. In the fourth Cu site, Cu(4) is bonded in a distorted square co-planar geometry to one O(2), one O(6), and two equivalent O(9) atoms. There are ten inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Nd(3), two equivalent Nd(4), one Cu(1), and one Cu(2) atom to form ONd4Cu2 octahedra that share corners with three equivalent O(4)Nd2Mg2Cu2 pentagonal pyramids, corners with two equivalent O(10)Nd3Cu2 trigonal bipyramids, edges with two equivalent O(1)Nd4Cu2 octahedra, and  a faceface with one O(4)Nd2Mg2Cu2 pentagonal pyramid. In the second O site, O(2) is bonded to two equivalent Nd(1), two equivalent Nd(2), one Cu(3), and one Cu(4) atom to form distorted ONd4Cu2 octahedra that share edges with two equivalent O(2)Nd4Cu2 octahedra and faces with two equivalent O(10)Nd3Cu2 trigonal bipyramids. In the third O site, O(3) is bonded in a 7-coordinate geometry to two equivalent Mg(1), two equivalent Nd(1), two equivalent Nd(3), and one Cu(1) atom. In the fourth O site, O(4) is bonded to two equivalent Mg(1), two equivalent Nd(4), one Cu(1), and one Cu(2) atom to form distorted ONd2Mg2Cu2 pentagonal pyramids that share corners with three equivalent O(1)Nd4Cu2 octahedra, edges with two equivalent O(4)Nd2Mg2Cu2 pentagonal pyramids, and  a faceface with one O(1)Nd4Cu2 octahedra. The corner-sharing octahedral tilt angles range from 34-53°. In the fifth O site, O(5) is bonded in a 6-coordinate geometry to two equivalent Nd(1), two equivalent Nd(3), one Cu(1), and one Cu(3) atom. In the sixth O site, O(6) is bonded in a 7-coordinate geometry to two equivalent Nd(2), two equivalent Nd(4), one Cu(2), one Cu(3), and one Cu(4) atom. In the seventh O site, O(7) is bonded in a 6-coordinate geometry to one Mg(1), one Nd(1), one Nd(3), one Nd(4), and two equivalent Cu(1) atoms. In the eighth O site, O(8) is bonded in a 5-coordinate geometry to one Mg(1), one Nd(2), one Nd(4), and two equivalent Cu(2) atoms. In the ninth O site, O(9) is bonded in a 5-coordinate geometry to one Nd(1), one Nd(2), one Nd(4), and two equivalent Cu(4) atoms. In the tenth O site, O(10) is bonded to one Nd(1), one Nd(2), one Nd(3), and two equivalent Cu(3) atoms to form ONd3Cu2 trigonal bipyramids that share corners with two equivalent O(1)Nd4Cu2 octahedra, corners with two equivalent O(10)Nd3Cu2 trigonal bipyramids, and faces with two equivalent O(2)Nd4Cu2 octahedra. The corner-sharing octahedral tilt angles are 47°.
MgNd4(Cu2O5)2 crystallizes in the monoclinic Pm space group. Mg(1) is bonded in a 6-coordinate geometry to one O(7), one O(8), two equivalent O(3), and two equivalent O(4) atoms. The Mg(1)-O(7) bond length is 1.97 Å. The Mg(1)-O(8) bond length is 1.97 Å. Both Mg(1)-O(3) bond lengths are 2.57 Å. Both Mg(1)-O(4) bond lengths are 2.31 Å. There are four inequivalent Nd sites. In the first Nd site, Nd(1) is bonded in a 9-coordinate geometry to one O(10), one O(7), one O(9), two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms. The Nd(1)-O(10) bond length is 2.55 Å. The Nd(1)-O(7) bond length is 2.48 Å. The Nd(1)-O(9) bond length is 2.76 Å. Both Nd(1)-O(2) bond lengths are 2.51 Å. Both Nd(1)-O(3) bond lengths are 2.98 Å. Both Nd(1)-O(5) bond lengths are 2.56 Å. In the second Nd site, Nd(2) is bonded in a 7-coordinate geometry to one O(10), one O(8), one O(9), two equivalent O(2), and two equivalent O(6) atoms. The Nd(2)-O(10) bond length is 2.43 Å. The Nd(2)-O(8) bond length is 2.46 Å. The Nd(2)-O(9) bond length is 2.52 Å. Both Nd(2)-O(2) bond lengths are 2.44 Å. Both Nd(2)-O(6) bond lengths are 2.65 Å. In the third Nd site, Nd(3) is bonded in a 8-coordinate geometry to one O(10), one O(7), two equivalent O(1), two equivalent O(3), and two equivalent O(5) atoms. The Nd(3)-O(10) bond length is 2.41 Å. The Nd(3)-O(7) bond length is 2.46 Å. Both Nd(3)-O(1) bond lengths are 2.54 Å. Both Nd(3)-O(3) bond lengths are 2.71 Å. Both Nd(3)-O(5) bond lengths are 2.72 Å. In the fourth Nd site, Nd(4) is bonded in a 9-coordinate geometry to one O(7), one O(8), one O(9), two equivalent O(1), two equivalent O(4), and two equivalent O(6) atoms. The Nd(4)-O(7) bond length is 2.86 Å. The Nd(4)-O(8) bond length is 2.46 Å. The Nd(4)-O(9) bond length is 2.46 Å. Both Nd(4)-O(1) bond lengths are 2.67 Å. Both Nd(4)-O(4) bond lengths are 2.63 Å. Both Nd(4)-O(6) bond lengths are 2.59 Å. There are four inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to one O(1), one O(3), one O(4), one O(5), and two equivalent O(7) atoms to form distorted CuO6 octahedra that share corners with two equivalent Cu(1)O6 octahedra and corners with two equivalent Cu(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 6°. The Cu(1)-O(1) bond length is 2.08 Å. The Cu(1)-O(3) bond length is 2.25 Å. The Cu(1)-O(4) bond length is 2.36 Å. The Cu(1)-O(5) bond length is 2.25 Å. Both Cu(1)-O(7) bond lengths are 1.86 Å. In the second Cu site, Cu(2) is bonded to one O(1), one O(4), one O(6), and two equivalent O(8) atoms to form distorted CuO5 trigonal bipyramids that share corners with two equivalent Cu(1)O6 octahedra and corners with two equivalent Cu(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 9-73°. The Cu(2)-O(1) bond length is 2.08 Å. The Cu(2)-O(4) bond length is 2.29 Å. The Cu(2)-O(6) bond length is 2.35 Å. Both Cu(2)-O(8) bond lengths are 1.86 Å. In the third Cu site, Cu(3) is bonded in a 3-coordinate geometry to one O(2), one O(5), one O(6), and two equivalent O(10) atoms. The Cu(3)-O(2) bond length is 2.52 Å. The Cu(3)-O(5) bond length is 2.10 Å. The Cu(3)-O(6) bond length is 2.64 Å. Both Cu(3)-O(10) bond lengths are 1.97 Å. In the fourth Cu site, Cu(4) is bonded in a distorted square co-planar geometry to one O(2), one O(6), and two equivalent O(9) atoms. The Cu(4)-O(2) bond length is 2.13 Å. The Cu(4)-O(6) bond length is 2.18 Å. Both Cu(4)-O(9) bond lengths are 1.91 Å. There are ten inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Nd(3), two equivalent Nd(4), one Cu(1), and one Cu(2) atom to form ONd4Cu2 octahedra that share corners with three equivalent O(4)Nd2Mg2Cu2 pentagonal pyramids, corners with two equivalent O(10)Nd3Cu2 trigonal bipyramids, edges with two equivalent O(1)Nd4Cu2 octahedra, and  a faceface with one O(4)Nd2Mg2Cu2 pentagonal pyramid. In the second O site, O(2) is bonded to two equivalent Nd(1), two equivalent Nd(2), one Cu(3), and one Cu(4) atom to form distorted ONd4Cu2 octahedra that share edges with two equivalent O(2)Nd4Cu2 octahedra and faces with two equivalent O(10)Nd3Cu2 trigonal bipyramids. In the third O site, O(3) is bonded in a 7-coordinate geometry to two equivalent Mg(1), two equivalent Nd(1), two equivalent Nd(3), and one Cu(1) atom. In the fourth O site, O(4) is bonded to two equivalent Mg(1), two equivalent Nd(4), one Cu(1), and one Cu(2) atom to form distorted ONd2Mg2Cu2 pentagonal pyramids that share corners with three equivalent O(1)Nd4Cu2 octahedra, edges with two equivalent O(4)Nd2Mg2Cu2 pentagonal pyramids, and  a faceface with one O(1)Nd4Cu2 octahedra. The corner-sharing octahedral tilt angles range from 34-53°. In the fifth O site, O(5) is bonded in a 6-coordinate geometry to two equivalent Nd(1), two equivalent Nd(3), one Cu(1), and one Cu(3) atom. In the sixth O site, O(6) is bonded in a 7-coordinate geometry to two equivalent Nd(2), two equivalent Nd(4), one Cu(2), one Cu(3), and one Cu(4) atom. In the seventh O site, O(7) is bonded in a 6-coordinate geometry to one Mg(1), one Nd(1), one Nd(3), one Nd(4), and two equivalent Cu(1) atoms. In the eighth O site, O(8) is bonded in a 5-coordinate geometry to one Mg(1), one Nd(2), one Nd(4), and two equivalent Cu(2) atoms. In the ninth O site, O(9) is bonded in a 5-coordinate geometry to one Nd(1), one Nd(2), one Nd(4), and two equivalent Cu(4) atoms. In the tenth O site, O(10) is bonded to one Nd(1), one Nd(2), one Nd(3), and two equivalent Cu(3) atoms to form ONd3Cu2 trigonal bipyramids that share corners with two equivalent O(1)Nd4Cu2 octahedra, corners with two equivalent O(10)Nd3Cu2 trigonal bipyramids, and faces with two equivalent O(2)Nd4Cu2 octahedra. The corner-sharing octahedral tilt angles are 47°.