MgCo2(MoO4)2 crystallizes in the monoclinic P2 space group. Mg(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form distorted MgO6 octahedra that share corners with four equivalent Mo(2)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, and edges with two equivalent Co(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 25-53°. There are two inequivalent Mo sites. In the first Mo site, Mo(1) is bonded in a 6-coordinate geometry to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms. In the second Mo site, Mo(2) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form distorted MoO6 octahedra that share corners with four equivalent Mg(1)O6 octahedra, corners with four equivalent Co(1)O6 octahedra, and corners with four equivalent Co(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 25-58°. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form distorted CoO6 octahedra that share corners with four equivalent Mo(2)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, and edges with two equivalent Co(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 45-58°. In the second Co site, Co(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form CoO6 octahedra that share corners with four equivalent Mo(2)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, and edges with two equivalent Co(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 46-52°. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), one Mo(1), one Co(1), and one Co(2) atom to form OMgCo2Mo trigonal pyramids that share corners with two equivalent O(1)MgCo2Mo trigonal pyramids, corners with two equivalent O(3)MgCoMo2 trigonal pyramids,  an edgeedge with one O(1)MgCo2Mo trigonal pyramid, and edges with two equivalent O(3)MgCoMo2 trigonal pyramids. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one Mo(2), one Co(1), and one Co(2) atom. In the third O site, O(3) is bonded to one Mg(1), one Mo(1), one Mo(2), and one Co(2) atom to form distorted OMgCoMo2 trigonal pyramids that share corners with two equivalent O(1)MgCo2Mo trigonal pyramids, corners with four equivalent O(3)MgCoMo2 trigonal pyramids, and edges with two equivalent O(1)MgCo2Mo trigonal pyramids. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Mg(1), one Mo(1), one Mo(2), and one Co(1) atom.
MgCo2(MoO4)2 crystallizes in the monoclinic P2 space group. Mg(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form distorted MgO6 octahedra that share corners with four equivalent Mo(2)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, and edges with two equivalent Co(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 25-53°. Both Mg(1)-O(1) bond lengths are 2.14 Å. Both Mg(1)-O(3) bond lengths are 2.05 Å. Both Mg(1)-O(4) bond lengths are 2.04 Å. There are two inequivalent Mo sites. In the first Mo site, Mo(1) is bonded in a 6-coordinate geometry to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms. Both Mo(1)-O(1) bond lengths are 1.95 Å. Both Mo(1)-O(3) bond lengths are 1.93 Å. Both Mo(1)-O(4) bond lengths are 2.22 Å. In the second Mo site, Mo(2) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form distorted MoO6 octahedra that share corners with four equivalent Mg(1)O6 octahedra, corners with four equivalent Co(1)O6 octahedra, and corners with four equivalent Co(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 25-58°. Both Mo(2)-O(2) bond lengths are 1.92 Å. Both Mo(2)-O(3) bond lengths are 2.20 Å. Both Mo(2)-O(4) bond lengths are 2.01 Å. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form distorted CoO6 octahedra that share corners with four equivalent Mo(2)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, and edges with two equivalent Co(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 45-58°. Both Co(1)-O(1) bond lengths are 2.09 Å. Both Co(1)-O(2) bond lengths are 2.06 Å. Both Co(1)-O(4) bond lengths are 2.36 Å. In the second Co site, Co(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form CoO6 octahedra that share corners with four equivalent Mo(2)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, and edges with two equivalent Co(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 46-52°. Both Co(2)-O(1) bond lengths are 2.01 Å. Both Co(2)-O(2) bond lengths are 2.05 Å. Both Co(2)-O(3) bond lengths are 2.48 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), one Mo(1), one Co(1), and one Co(2) atom to form OMgCo2Mo trigonal pyramids that share corners with two equivalent O(1)MgCo2Mo trigonal pyramids, corners with two equivalent O(3)MgCoMo2 trigonal pyramids,  an edgeedge with one O(1)MgCo2Mo trigonal pyramid, and edges with two equivalent O(3)MgCoMo2 trigonal pyramids. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one Mo(2), one Co(1), and one Co(2) atom. In the third O site, O(3) is bonded to one Mg(1), one Mo(1), one Mo(2), and one Co(2) atom to form distorted OMgCoMo2 trigonal pyramids that share corners with two equivalent O(1)MgCo2Mo trigonal pyramids, corners with four equivalent O(3)MgCoMo2 trigonal pyramids, and edges with two equivalent O(1)MgCo2Mo trigonal pyramids. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Mg(1), one Mo(1), one Mo(2), and one Co(1) atom.