MgMn2(PO4)2 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(1), one O(2), one O(3), one O(5), one O(6), and one O(8) atom to form MgO6 octahedra that share corners with three equivalent Mn(1)O5 square pyramids, corners with three equivalent Mn(2)O5 square pyramids,  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(2)O4 tetrahedra,  an edgeedge with one P(1)O4 tetrahedra, and  an edgeedge with one P(2)O4 tetrahedra. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one O(2), one O(4), one O(5), one O(6), and one O(7) atom to form distorted MnO5 square pyramids that share corners with three equivalent Mg(1)O6 octahedra, corners with two equivalent P(2)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra, and  an edgeedge with one Mn(2)O5 square pyramid. The corner-sharing octahedral tilt angles range from 59-62°. In the second Mn site, Mn(2) is bonded to one O(1), one O(3), one O(4), one O(7), and one O(8) atom to form distorted MnO5 square pyramids that share corners with three equivalent Mg(1)O6 octahedra, corners with two equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra, and  an edgeedge with one Mn(1)O5 square pyramid. The corner-sharing octahedral tilt angles range from 59-62°. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(2), one O(3), one O(4), and one O(6) atom to form PO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra, corners with two equivalent Mn(2)O5 square pyramids, corners with three equivalent Mn(1)O5 square pyramids, and  an edgeedge with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles are 56°. In the second P site, P(2) is bonded to one O(1), one O(5), one O(7), and one O(8) atom to form PO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra, corners with two equivalent Mn(1)O5 square pyramids, corners with three equivalent Mn(2)O5 square pyramids, and  an edgeedge with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles are 55°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Mg(1), one Mn(2), and one P(2) atom. 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 distorted trigonal planar geometry to one Mg(1), one Mn(2), and one P(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Mn(1), one Mn(2), and one P(1) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Mg(1), one Mn(1), and one P(2) atom. In the sixth O site, O(6) is bonded in a trigonal planar geometry to one Mg(1), one Mn(1), and one P(1) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Mn(1), one Mn(2), and one P(2) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Mg(1), one Mn(2), and one P(2) atom.
MgMn2(PO4)2 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(1), one O(2), one O(3), one O(5), one O(6), and one O(8) atom to form MgO6 octahedra that share corners with three equivalent Mn(1)O5 square pyramids, corners with three equivalent Mn(2)O5 square pyramids,  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(2)O4 tetrahedra,  an edgeedge with one P(1)O4 tetrahedra, and  an edgeedge with one P(2)O4 tetrahedra. The Mg(1)-O(1) bond length is 2.14 Å. The Mg(1)-O(2) bond length is 2.34 Å. The Mg(1)-O(3) bond length is 2.01 Å. The Mg(1)-O(5) bond length is 2.02 Å. The Mg(1)-O(6) bond length is 2.14 Å. The Mg(1)-O(8) bond length is 2.31 Å. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one O(2), one O(4), one O(5), one O(6), and one O(7) atom to form distorted MnO5 square pyramids that share corners with three equivalent Mg(1)O6 octahedra, corners with two equivalent P(2)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra, and  an edgeedge with one Mn(2)O5 square pyramid. The corner-sharing octahedral tilt angles range from 59-62°. The Mn(1)-O(2) bond length is 2.17 Å. The Mn(1)-O(4) bond length is 2.25 Å. The Mn(1)-O(5) bond length is 2.14 Å. The Mn(1)-O(6) bond length is 2.19 Å. The Mn(1)-O(7) bond length is 2.15 Å. In the second Mn site, Mn(2) is bonded to one O(1), one O(3), one O(4), one O(7), and one O(8) atom to form distorted MnO5 square pyramids that share corners with three equivalent Mg(1)O6 octahedra, corners with two equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra, and  an edgeedge with one Mn(1)O5 square pyramid. The corner-sharing octahedral tilt angles range from 59-62°. The Mn(2)-O(1) bond length is 2.19 Å. The Mn(2)-O(3) bond length is 2.14 Å. The Mn(2)-O(4) bond length is 2.15 Å. The Mn(2)-O(7) bond length is 2.25 Å. The Mn(2)-O(8) bond length is 2.18 Å. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(2), one O(3), one O(4), and one O(6) atom to form PO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra, corners with two equivalent Mn(2)O5 square pyramids, corners with three equivalent Mn(1)O5 square pyramids, and  an edgeedge with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles are 56°. The P(1)-O(2) bond length is 1.55 Å. The P(1)-O(3) bond length is 1.56 Å. The P(1)-O(4) bond length is 1.56 Å. The P(1)-O(6) bond length is 1.56 Å. In the second P site, P(2) is bonded to one O(1), one O(5), one O(7), and one O(8) atom to form PO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra, corners with two equivalent Mn(1)O5 square pyramids, corners with three equivalent Mn(2)O5 square pyramids, and  an edgeedge with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles are 55°. The P(2)-O(1) bond length is 1.56 Å. The P(2)-O(5) bond length is 1.56 Å. The P(2)-O(7) bond length is 1.56 Å. The P(2)-O(8) bond length is 1.55 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Mg(1), one Mn(2), and one P(2) atom. 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 distorted trigonal planar geometry to one Mg(1), one Mn(2), and one P(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Mn(1), one Mn(2), and one P(1) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Mg(1), one Mn(1), and one P(2) atom. In the sixth O site, O(6) is bonded in a trigonal planar geometry to one Mg(1), one Mn(1), and one P(1) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Mn(1), one Mn(2), and one P(2) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Mg(1), one Mn(2), and one P(2) atom.