MgMnP2O7 crystallizes in the monoclinic C2 space group. Mg(1) is bonded in a 7-coordinate geometry to one O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. Mn(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form MnO6 octahedra that share corners with six equivalent P(1)O4 tetrahedra. P(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form PO4 tetrahedra that share corners with three equivalent Mn(1)O6 octahedra and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 34-59°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Mg(1) and two equivalent P(1) atoms. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Mg(1), one Mn(1), and one P(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Mg(1), one Mn(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Mg(1), one Mn(1), and one P(1) atom.
MgMnP2O7 crystallizes in the monoclinic C2 space group. Mg(1) is bonded in a 7-coordinate geometry to one O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. The Mg(1)-O(1) bond length is 2.10 Å. Both Mg(1)-O(2) bond lengths are 2.17 Å. Both Mg(1)-O(3) bond lengths are 2.16 Å. Both Mg(1)-O(4) bond lengths are 2.61 Å. Mn(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form MnO6 octahedra that share corners with six equivalent P(1)O4 tetrahedra. Both Mn(1)-O(2) bond lengths are 2.23 Å. Both Mn(1)-O(3) bond lengths are 2.23 Å. Both Mn(1)-O(4) bond lengths are 2.25 Å. P(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form PO4 tetrahedra that share corners with three equivalent Mn(1)O6 octahedra and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 34-59°. The P(1)-O(1) bond length is 1.65 Å. The P(1)-O(2) bond length is 1.54 Å. The P(1)-O(3) bond length is 1.54 Å. The P(1)-O(4) bond length is 1.52 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Mg(1) and two equivalent P(1) atoms. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Mg(1), one Mn(1), and one P(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Mg(1), one Mn(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Mg(1), one Mn(1), and one P(1) atom.