MgMo2O7 crystallizes in the monoclinic P2_1/c space group. Mg(1) is bonded to one O(3), one O(4), one O(5), one O(7), and two equivalent O(2) atoms to form MgO6 octahedra that share corners with three equivalent Mo(1)O4 tetrahedra, corners with three equivalent Mo(2)O4 tetrahedra, and  an edgeedge with one Mg(1)O6 octahedra. There are two inequivalent Mo sites. In the first Mo site, Mo(1) is bonded to one O(1), one O(2), one O(3), and one O(6) atom to form MoO4 tetrahedra that share corners with three equivalent Mg(1)O6 octahedra and  a cornercorner with one Mo(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 25-60°. In the second Mo site, Mo(2) is bonded to one O(4), one O(5), one O(6), and one O(7) atom to form MoO4 tetrahedra that share corners with three equivalent Mg(1)O6 octahedra and  a cornercorner with one Mo(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 10-33°. There are seven inequivalent O sites. In the first O site, O(6) is bonded in a bent 150 degrees geometry to one Mo(1) and one Mo(2) atom. In the second O site, O(7) is bonded in a bent 150 degrees geometry to one Mg(1) and one Mo(2) atom. In the third O site, O(1) is bonded in a single-bond geometry to one Mo(1) atom. In the fourth O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Mg(1) and one Mo(1) atom. In the fifth O site, O(3) is bonded in a bent 150 degrees geometry to one Mg(1) and one Mo(1) atom. In the sixth O site, O(4) is bonded in a bent 150 degrees geometry to one Mg(1) and one Mo(2) atom. In the seventh O site, O(5) is bonded in a linear geometry to one Mg(1) and one Mo(2) atom.
MgMo2O7 crystallizes in the monoclinic P2_1/c space group. Mg(1) is bonded to one O(3), one O(4), one O(5), one O(7), and two equivalent O(2) atoms to form MgO6 octahedra that share corners with three equivalent Mo(1)O4 tetrahedra, corners with three equivalent Mo(2)O4 tetrahedra, and  an edgeedge with one Mg(1)O6 octahedra. The Mg(1)-O(3) bond length is 2.05 Å. The Mg(1)-O(4) bond length is 2.06 Å. The Mg(1)-O(5) bond length is 2.03 Å. The Mg(1)-O(7) bond length is 2.05 Å. There is one shorter (2.07 Å) and one longer (2.12 Å) Mg(1)-O(2) bond length. There are two inequivalent Mo sites. In the first Mo site, Mo(1) is bonded to one O(1), one O(2), one O(3), and one O(6) atom to form MoO4 tetrahedra that share corners with three equivalent Mg(1)O6 octahedra and  a cornercorner with one Mo(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 25-60°. The Mo(1)-O(1) bond length is 1.70 Å. The Mo(1)-O(2) bond length is 1.78 Å. The Mo(1)-O(3) bond length is 1.73 Å. The Mo(1)-O(6) bond length is 1.89 Å. In the second Mo site, Mo(2) is bonded to one O(4), one O(5), one O(6), and one O(7) atom to form MoO4 tetrahedra that share corners with three equivalent Mg(1)O6 octahedra and  a cornercorner with one Mo(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 10-33°. The Mo(2)-O(4) bond length is 1.75 Å. The Mo(2)-O(5) bond length is 1.72 Å. The Mo(2)-O(6) bond length is 1.87 Å. The Mo(2)-O(7) bond length is 1.72 Å. There are seven inequivalent O sites. In the first O site, O(6) is bonded in a bent 150 degrees geometry to one Mo(1) and one Mo(2) atom. In the second O site, O(7) is bonded in a bent 150 degrees geometry to one Mg(1) and one Mo(2) atom. In the third O site, O(1) is bonded in a single-bond geometry to one Mo(1) atom. In the fourth O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Mg(1) and one Mo(1) atom. In the fifth O site, O(3) is bonded in a bent 150 degrees geometry to one Mg(1) and one Mo(1) atom. In the sixth O site, O(4) is bonded in a bent 150 degrees geometry to one Mg(1) and one Mo(2) atom. In the seventh O site, O(5) is bonded in a linear geometry to one Mg(1) and one Mo(2) atom.