Mg3Mo2O7 is Hausmannite-derived structured and crystallizes in the orthorhombic Cmc2_1 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent O(3) and two equivalent O(4) atoms to form distorted MgO4 tetrahedra that share corners with eight equivalent Mo(1)O6 octahedra and corners with two equivalent Mg(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 64-82°. In the second Mg site, Mg(2) is bonded in a 4-coordinate geometry to one O(2), one O(3), and three equivalent O(1) atoms. Mo(1) is bonded to one O(1), one O(4), two equivalent O(2), and two equivalent O(3) atoms to form MoO6 octahedra that share corners with five equivalent Mo(1)O6 octahedra and corners with four equivalent Mg(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 45-47°. There are four inequivalent O sites. In the first O site, O(1) is bonded to three equivalent Mg(2) and one Mo(1) atom to form OMg3Mo tetrahedra that share  a cornercorner with one O(4)Mg2Mo2 tetrahedra and corners with six equivalent O(1)Mg3Mo tetrahedra. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Mg(2) and two equivalent Mo(1) atoms. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Mg(1), one Mg(2), and two equivalent Mo(1) atoms. In the fourth O site, O(4) is bonded to two equivalent Mg(1) and two equivalent Mo(1) atoms to form distorted OMg2Mo2 tetrahedra that share corners with two equivalent O(4)Mg2Mo2 tetrahedra and corners with two equivalent O(1)Mg3Mo tetrahedra.
Mg3Mo2O7 is Hausmannite-derived structured and crystallizes in the orthorhombic Cmc2_1 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent O(3) and two equivalent O(4) atoms to form distorted MgO4 tetrahedra that share corners with eight equivalent Mo(1)O6 octahedra and corners with two equivalent Mg(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 64-82°. Both Mg(1)-O(3) bond lengths are 2.06 Å. There is one shorter (2.04 Å) and one longer (2.11 Å) Mg(1)-O(4) bond length. In the second Mg site, Mg(2) is bonded in a 4-coordinate geometry to one O(2), one O(3), and three equivalent O(1) atoms. The Mg(2)-O(2) bond length is 2.05 Å. The Mg(2)-O(3) bond length is 2.49 Å. There are a spread of Mg(2)-O(1) bond distances ranging from 2.01-2.07 Å. Mo(1) is bonded to one O(1), one O(4), two equivalent O(2), and two equivalent O(3) atoms to form MoO6 octahedra that share corners with five equivalent Mo(1)O6 octahedra and corners with four equivalent Mg(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 45-47°. The Mo(1)-O(1) bond length is 2.07 Å. The Mo(1)-O(4) bond length is 2.13 Å. There is one shorter (2.02 Å) and one longer (2.11 Å) Mo(1)-O(2) bond length. There is one shorter (2.04 Å) and one longer (2.11 Å) Mo(1)-O(3) bond length. There are four inequivalent O sites. In the first O site, O(1) is bonded to three equivalent Mg(2) and one Mo(1) atom to form OMg3Mo tetrahedra that share  a cornercorner with one O(4)Mg2Mo2 tetrahedra and corners with six equivalent O(1)Mg3Mo tetrahedra. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Mg(2) and two equivalent Mo(1) atoms. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Mg(1), one Mg(2), and two equivalent Mo(1) atoms. In the fourth O site, O(4) is bonded to two equivalent Mg(1) and two equivalent Mo(1) atoms to form distorted OMg2Mo2 tetrahedra that share corners with two equivalent O(4)Mg2Mo2 tetrahedra and corners with two equivalent O(1)Mg3Mo tetrahedra.