Mg(MoO2)4 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(4), one O(5), and two equivalent O(2) atoms to form distorted MgO4 tetrahedra that share  a cornercorner with one Mo(2)O6 octahedra,  a cornercorner with one Mo(4)O6 octahedra, corners with two equivalent Mo(3)O6 octahedra, corners with two equivalent Mg(1)O4 tetrahedra, and  an edgeedge with one Mo(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 6-39°. There are four inequivalent Mo sites. In the first Mo site, Mo(1) is bonded in a 5-coordinate geometry to one O(7), two equivalent O(4), and two equivalent O(5) atoms. In the second Mo site, Mo(2) is bonded to one O(4), one O(8), two equivalent O(3), and two equivalent O(6) atoms to form MoO6 octahedra that share corners with two equivalent Mo(4)O6 octahedra,  a cornercorner with one Mg(1)O4 tetrahedra, edges with two equivalent Mo(2)O6 octahedra, and edges with two equivalent Mo(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 47-54°. In the third Mo site, Mo(3) is bonded to one O(1), one O(6), two equivalent O(2), and two equivalent O(8) atoms to form MoO6 octahedra that share corners with two equivalent Mo(4)O6 octahedra, corners with two equivalent Mg(1)O4 tetrahedra, edges with two equivalent Mo(2)O6 octahedra, edges with two equivalent Mo(3)O6 octahedra, and  an edgeedge with one Mg(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 50-53°. In the fourth Mo site, Mo(4) is bonded to one O(3), one O(5), two equivalent O(1), and two equivalent O(7) atoms to form MoO6 octahedra that share corners with two equivalent Mo(2)O6 octahedra, corners with two equivalent Mo(3)O6 octahedra,  a cornercorner with one Mg(1)O4 tetrahedra, and edges with two equivalent Mo(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 47-54°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Mo(3) and two equivalent Mo(4) atoms. In the second O site, O(2) is bonded in a rectangular see-saw-like geometry to two equivalent Mg(1) and two equivalent Mo(3) atoms. In the third O site, O(3) is bonded in a trigonal planar geometry to one Mo(4) and two equivalent Mo(2) atoms. In the fourth O site, O(4) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), one Mo(2), and two equivalent Mo(1) atoms. In the fifth O site, O(5) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Mo(4), and two equivalent Mo(1) atoms. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Mo(3) and two equivalent Mo(2) atoms. In the seventh O site, O(7) is bonded in a trigonal non-coplanar geometry to one Mo(1) and two equivalent Mo(4) atoms. In the eighth O site, O(8) is bonded in a trigonal non-coplanar geometry to one Mo(2) and two equivalent Mo(3) atoms.
Mg(MoO2)4 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(4), one O(5), and two equivalent O(2) atoms to form distorted MgO4 tetrahedra that share  a cornercorner with one Mo(2)O6 octahedra,  a cornercorner with one Mo(4)O6 octahedra, corners with two equivalent Mo(3)O6 octahedra, corners with two equivalent Mg(1)O4 tetrahedra, and  an edgeedge with one Mo(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 6-39°. The Mg(1)-O(4) bond length is 2.13 Å. The Mg(1)-O(5) bond length is 2.09 Å. Both Mg(1)-O(2) bond lengths are 2.00 Å. There are four inequivalent Mo sites. In the first Mo site, Mo(1) is bonded in a 5-coordinate geometry to one O(7), two equivalent O(4), and two equivalent O(5) atoms. The Mo(1)-O(7) bond length is 2.02 Å. Both Mo(1)-O(4) bond lengths are 2.16 Å. Both Mo(1)-O(5) bond lengths are 2.20 Å. In the second Mo site, Mo(2) is bonded to one O(4), one O(8), two equivalent O(3), and two equivalent O(6) atoms to form MoO6 octahedra that share corners with two equivalent Mo(4)O6 octahedra,  a cornercorner with one Mg(1)O4 tetrahedra, edges with two equivalent Mo(2)O6 octahedra, and edges with two equivalent Mo(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 47-54°. The Mo(2)-O(4) bond length is 2.07 Å. The Mo(2)-O(8) bond length is 2.00 Å. There is one shorter (2.06 Å) and one longer (2.15 Å) Mo(2)-O(3) bond length. Both Mo(2)-O(6) bond lengths are 2.12 Å. In the third Mo site, Mo(3) is bonded to one O(1), one O(6), two equivalent O(2), and two equivalent O(8) atoms to form MoO6 octahedra that share corners with two equivalent Mo(4)O6 octahedra, corners with two equivalent Mg(1)O4 tetrahedra, edges with two equivalent Mo(2)O6 octahedra, edges with two equivalent Mo(3)O6 octahedra, and  an edgeedge with one Mg(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 50-53°. The Mo(3)-O(1) bond length is 2.15 Å. The Mo(3)-O(6) bond length is 2.17 Å. There is one shorter (2.30 Å) and one longer (2.31 Å) Mo(3)-O(2) bond length. There is one shorter (2.11 Å) and one longer (2.12 Å) Mo(3)-O(8) bond length. In the fourth Mo site, Mo(4) is bonded to one O(3), one O(5), two equivalent O(1), and two equivalent O(7) atoms to form MoO6 octahedra that share corners with two equivalent Mo(2)O6 octahedra, corners with two equivalent Mo(3)O6 octahedra,  a cornercorner with one Mg(1)O4 tetrahedra, and edges with two equivalent Mo(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 47-54°. The Mo(4)-O(3) bond length is 2.01 Å. The Mo(4)-O(5) bond length is 2.14 Å. There is one shorter (1.99 Å) and one longer (2.16 Å) Mo(4)-O(1) bond length. Both Mo(4)-O(7) bond lengths are 2.13 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Mo(3) and two equivalent Mo(4) atoms. In the second O site, O(2) is bonded in a rectangular see-saw-like geometry to two equivalent Mg(1) and two equivalent Mo(3) atoms. In the third O site, O(3) is bonded in a trigonal planar geometry to one Mo(4) and two equivalent Mo(2) atoms. In the fourth O site, O(4) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), one Mo(2), and two equivalent Mo(1) atoms. In the fifth O site, O(5) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Mo(4), and two equivalent Mo(1) atoms. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Mo(3) and two equivalent Mo(2) atoms. In the seventh O site, O(7) is bonded in a trigonal non-coplanar geometry to one Mo(1) and two equivalent Mo(4) atoms. In the eighth O site, O(8) is bonded in a trigonal non-coplanar geometry to one Mo(2) and two equivalent Mo(3) atoms.