MgCd2(MoO4)2 crystallizes in the monoclinic C2 space group. Mg(1) is bonded to two equivalent O(1) and two equivalent O(3) atoms to form MgO4 tetrahedra that share corners with two equivalent Mo(2)O6 octahedra and  an edgeedge with one Mo(1)O6 octahedra. The corner-sharing octahedral tilt angles are 51°. There are two inequivalent Mo sites. In the first Mo site, Mo(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form MoO6 octahedra that share edges with two equivalent Mo(2)O6 octahedra and  an edgeedge with one Mg(1)O4 tetrahedra. In the second Mo site, Mo(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form distorted MoO6 octahedra that share corners with two equivalent Mg(1)O4 tetrahedra and edges with two equivalent Mo(1)O6 octahedra. There are two inequivalent Cd sites. In the first Cd site, Cd(1) is bonded in a 6-coordinate geometry to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. In the second Cd site, Cd(2) is bonded in a 6-coordinate geometry to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms. There are four inequivalent O sites. In the first O site, O(1) is bonded in a trigonal non-coplanar geometry to one Mg(1), one Mo(2), and one Cd(2) atom. In the second O site, O(2) is bonded to one Mo(1), one Mo(2), one Cd(1), and one Cd(2) atom to form distorted corner-sharing OCd2Mo2 trigonal pyramids. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one Mg(1), one Mo(1), and one Cd(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Mo(1), one Mo(2), one Cd(1), and one Cd(2) atom.
MgCd2(MoO4)2 crystallizes in the monoclinic C2 space group. Mg(1) is bonded to two equivalent O(1) and two equivalent O(3) atoms to form MgO4 tetrahedra that share corners with two equivalent Mo(2)O6 octahedra and  an edgeedge with one Mo(1)O6 octahedra. The corner-sharing octahedral tilt angles are 51°. Both Mg(1)-O(1) bond lengths are 1.98 Å. Both Mg(1)-O(3) bond lengths are 2.00 Å. There are two inequivalent Mo sites. In the first Mo site, Mo(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form MoO6 octahedra that share edges with two equivalent Mo(2)O6 octahedra and  an edgeedge with one Mg(1)O4 tetrahedra. Both Mo(1)-O(2) bond lengths are 1.94 Å. Both Mo(1)-O(3) bond lengths are 1.94 Å. Both Mo(1)-O(4) bond lengths are 2.18 Å. In the second Mo site, Mo(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form distorted MoO6 octahedra that share corners with two equivalent Mg(1)O4 tetrahedra and edges with two equivalent Mo(1)O6 octahedra. Both Mo(2)-O(1) bond lengths are 1.94 Å. Both Mo(2)-O(2) bond lengths are 2.25 Å. Both Mo(2)-O(4) bond lengths are 1.93 Å. There are two inequivalent Cd sites. In the first Cd site, Cd(1) is bonded in a 6-coordinate geometry to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. Both Cd(1)-O(2) bond lengths are 2.36 Å. Both Cd(1)-O(3) bond lengths are 2.20 Å. Both Cd(1)-O(4) bond lengths are 2.74 Å. In the second Cd site, Cd(2) is bonded in a 6-coordinate geometry to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms. Both Cd(2)-O(1) bond lengths are 2.24 Å. Both Cd(2)-O(2) bond lengths are 2.48 Å. Both Cd(2)-O(4) bond lengths are 2.26 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a trigonal non-coplanar geometry to one Mg(1), one Mo(2), and one Cd(2) atom. In the second O site, O(2) is bonded to one Mo(1), one Mo(2), one Cd(1), and one Cd(2) atom to form distorted corner-sharing OCd2Mo2 trigonal pyramids. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one Mg(1), one Mo(1), and one Cd(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Mo(1), one Mo(2), one Cd(1), and one Cd(2) atom.