MgMn3(CuO4)2 crystallizes in the triclinic P-1 space group. Mg(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form MgO6 octahedra that share corners with four equivalent Mn(1)O6 octahedra, corners with four equivalent Mn(2)O6 octahedra, corners with two equivalent Cu(1)O5 trigonal bipyramids, edges with two equivalent Cu(1)O5 trigonal bipyramids, and faces with two equivalent Mn(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 40-52°. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form distorted MnO6 octahedra that share corners with four equivalent Mg(1)O6 octahedra, corners with four equivalent Cu(1)O5 trigonal bipyramids, edges with four equivalent Mn(2)O6 octahedra, and edges with two equivalent Cu(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 40-52°. In the second Mn site, Mn(2) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms to form distorted MnO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with six equivalent Cu(1)O5 trigonal bipyramids, edges with two equivalent Mn(1)O6 octahedra, edges with two equivalent Mn(2)O6 octahedra, and  a faceface with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 45-51°. Cu(1) is bonded to one O(2), two equivalent O(3), and two equivalent O(4) atoms to form distorted CuO5 trigonal bipyramids that share  a cornercorner with one Mg(1)O6 octahedra, corners with two equivalent Mn(1)O6 octahedra, corners with six equivalent Mn(2)O6 octahedra,  an edgeedge with one Mg(1)O6 octahedra,  an edgeedge with one Mn(1)O6 octahedra, and edges with two equivalent Cu(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 44-79°. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), one Mn(1), and two equivalent Mn(2) atoms to form OMgMn3 trigonal pyramids that share corners with two equivalent O(4)MgMn2Cu2 trigonal bipyramids, corners with two equivalent O(1)MgMn3 trigonal pyramids, corners with two equivalent O(3)Mn2Cu2 trigonal pyramids, edges with two equivalent O(4)MgMn2Cu2 trigonal bipyramids,  an edgeedge with one O(1)MgMn3 trigonal pyramid, and  an edgeedge with one O(3)Mn2Cu2 trigonal pyramid. In the second O site, O(2) is bonded in a distorted see-saw-like geometry to one Mg(1), two equivalent Mn(2), and one Cu(1) atom. In the third O site, O(3) is bonded to one Mn(1), one Mn(2), and two equivalent Cu(1) atoms to form OMn2Cu2 trigonal pyramids that share corners with five equivalent O(4)MgMn2Cu2 trigonal bipyramids,  a cornercorner with one O(3)Mn2Cu2 trigonal pyramid, corners with two equivalent O(1)MgMn3 trigonal pyramids,  an edgeedge with one O(4)MgMn2Cu2 trigonal bipyramid,  an edgeedge with one O(1)MgMn3 trigonal pyramid, and  an edgeedge with one O(3)Mn2Cu2 trigonal pyramid. In the fourth O site, O(4) is bonded to one Mg(1), one Mn(1), one Mn(2), and two equivalent Cu(1) atoms to form distorted OMgMn2Cu2 trigonal bipyramids that share corners with two equivalent O(4)MgMn2Cu2 trigonal bipyramids, corners with two equivalent O(1)MgMn3 trigonal pyramids, corners with five equivalent O(3)Mn2Cu2 trigonal pyramids,  an edgeedge with one O(4)MgMn2Cu2 trigonal bipyramid,  an edgeedge with one O(3)Mn2Cu2 trigonal pyramid, and edges with two equivalent O(1)MgMn3 trigonal pyramids.
MgMn3(CuO4)2 crystallizes in the triclinic P-1 space group. Mg(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form MgO6 octahedra that share corners with four equivalent Mn(1)O6 octahedra, corners with four equivalent Mn(2)O6 octahedra, corners with two equivalent Cu(1)O5 trigonal bipyramids, edges with two equivalent Cu(1)O5 trigonal bipyramids, and faces with two equivalent Mn(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 40-52°. Both Mg(1)-O(1) bond lengths are 2.17 Å. Both Mg(1)-O(2) bond lengths are 2.03 Å. Both Mg(1)-O(4) bond lengths are 2.15 Å. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form distorted MnO6 octahedra that share corners with four equivalent Mg(1)O6 octahedra, corners with four equivalent Cu(1)O5 trigonal bipyramids, edges with four equivalent Mn(2)O6 octahedra, and edges with two equivalent Cu(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 40-52°. Both Mn(1)-O(1) bond lengths are 1.98 Å. Both Mn(1)-O(3) bond lengths are 2.02 Å. Both Mn(1)-O(4) bond lengths are 2.32 Å. In the second Mn site, Mn(2) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms to form distorted MnO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with six equivalent Cu(1)O5 trigonal bipyramids, edges with two equivalent Mn(1)O6 octahedra, edges with two equivalent Mn(2)O6 octahedra, and  a faceface with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 45-51°. The Mn(2)-O(3) bond length is 2.12 Å. The Mn(2)-O(4) bond length is 2.35 Å. There is one shorter (1.99 Å) and one longer (2.00 Å) Mn(2)-O(1) bond length. There is one shorter (1.89 Å) and one longer (1.96 Å) Mn(2)-O(2) bond length. Cu(1) is bonded to one O(2), two equivalent O(3), and two equivalent O(4) atoms to form distorted CuO5 trigonal bipyramids that share  a cornercorner with one Mg(1)O6 octahedra, corners with two equivalent Mn(1)O6 octahedra, corners with six equivalent Mn(2)O6 octahedra,  an edgeedge with one Mg(1)O6 octahedra,  an edgeedge with one Mn(1)O6 octahedra, and edges with two equivalent Cu(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 44-79°. The Cu(1)-O(2) bond length is 2.35 Å. There is one shorter (1.93 Å) and one longer (1.96 Å) Cu(1)-O(3) bond length. Both Cu(1)-O(4) bond lengths are 1.96 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), one Mn(1), and two equivalent Mn(2) atoms to form OMgMn3 trigonal pyramids that share corners with two equivalent O(4)MgMn2Cu2 trigonal bipyramids, corners with two equivalent O(1)MgMn3 trigonal pyramids, corners with two equivalent O(3)Mn2Cu2 trigonal pyramids, edges with two equivalent O(4)MgMn2Cu2 trigonal bipyramids,  an edgeedge with one O(1)MgMn3 trigonal pyramid, and  an edgeedge with one O(3)Mn2Cu2 trigonal pyramid. In the second O site, O(2) is bonded in a distorted see-saw-like geometry to one Mg(1), two equivalent Mn(2), and one Cu(1) atom. In the third O site, O(3) is bonded to one Mn(1), one Mn(2), and two equivalent Cu(1) atoms to form OMn2Cu2 trigonal pyramids that share corners with five equivalent O(4)MgMn2Cu2 trigonal bipyramids,  a cornercorner with one O(3)Mn2Cu2 trigonal pyramid, corners with two equivalent O(1)MgMn3 trigonal pyramids,  an edgeedge with one O(4)MgMn2Cu2 trigonal bipyramid,  an edgeedge with one O(1)MgMn3 trigonal pyramid, and  an edgeedge with one O(3)Mn2Cu2 trigonal pyramid. In the fourth O site, O(4) is bonded to one Mg(1), one Mn(1), one Mn(2), and two equivalent Cu(1) atoms to form distorted OMgMn2Cu2 trigonal bipyramids that share corners with two equivalent O(4)MgMn2Cu2 trigonal bipyramids, corners with two equivalent O(1)MgMn3 trigonal pyramids, corners with five equivalent O(3)Mn2Cu2 trigonal pyramids,  an edgeedge with one O(4)MgMn2Cu2 trigonal bipyramid,  an edgeedge with one O(3)Mn2Cu2 trigonal pyramid, and edges with two equivalent O(1)MgMn3 trigonal pyramids.