MnFe3(PO4)4 crystallizes in the monoclinic Pm space group. Mn(1) is bonded to one O(12), one O(4), two equivalent O(2), and two equivalent O(8) atoms to form distorted MnO6 pentagonal pyramids that share corners with four equivalent Fe(2)O6 octahedra,  a cornercorner with one P(3)O4 tetrahedra,  a cornercorner with one P(4)O4 tetrahedra, corners with two equivalent P(1)O4 tetrahedra, and  an edgeedge with one P(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 49-50°. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(3), one O(7), two equivalent O(11), and two equivalent O(5) atoms to form distorted FeO6 octahedra that share corners with four equivalent Fe(3)O6 octahedra,  a cornercorner with one P(3)O4 tetrahedra,  a cornercorner with one P(4)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, and  an edgeedge with one P(4)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 48-49°. In the second Fe site, Fe(2) is bonded to one O(10), one O(6), two equivalent O(2), and two equivalent O(8) atoms to form distorted FeO6 octahedra that share corners with four equivalent Mn(1)O6 pentagonal pyramids,  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(2)O4 tetrahedra, corners with two equivalent P(3)O4 tetrahedra, and  an edgeedge with one P(1)O4 tetrahedra. In the third Fe site, Fe(3) is bonded to one O(1), one O(9), two equivalent O(11), and two equivalent O(5) atoms to form distorted FeO6 octahedra that share corners with four equivalent Fe(1)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(2)O4 tetrahedra, corners with two equivalent P(4)O4 tetrahedra, and  an edgeedge with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 48-49°. There are four inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(10), and two equivalent O(2) atoms to form PO4 tetrahedra that share  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one Fe(3)O6 octahedra, corners with two equivalent Mn(1)O6 pentagonal pyramids, and  an edgeedge with one Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 40-44°. In the second P site, P(2) is bonded to one O(6), one O(9), and two equivalent O(5) atoms to form PO4 tetrahedra that share  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one Fe(3)O6 octahedra, corners with two equivalent Fe(1)O6 octahedra, and  an edgeedge with one Fe(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 42-56°. In the third P site, P(3) is bonded to one O(4), one O(7), and two equivalent O(8) atoms to form PO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra,  a cornercorner with one Mn(1)O6 pentagonal pyramid, and  an edgeedge with one Mn(1)O6 pentagonal pyramid. The corner-sharing octahedral tilt angles range from 37-53°. In the fourth P site, P(4) is bonded to one O(12), one O(3), and two equivalent O(11) atoms to form PO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra, corners with two equivalent Fe(3)O6 octahedra,  a cornercorner with one Mn(1)O6 pentagonal pyramid, and  an edgeedge with one Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 45-56°. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Fe(3) and one P(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Mn(1), one Fe(2), and one P(1) atom. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to one Fe(1) and one P(4) atom. In the fourth O site, O(4) is bonded in a bent 120 degrees geometry to one Mn(1) and one P(3) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Fe(1), one Fe(3), and one P(2) atom. In the sixth O site, O(6) is bonded in a distorted bent 150 degrees geometry to one Fe(2) and one P(2) atom. In the seventh O site, O(7) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(3) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Mn(1), one Fe(2), and one P(3) atom. In the ninth O site, O(9) is bonded in a distorted bent 150 degrees geometry to one Fe(3) and one P(2) atom. In the tenth O site, O(10) is bonded in a distorted bent 150 degrees geometry to one Fe(2) and one P(1) atom. In the eleventh O site, O(11) is bonded in a distorted trigonal planar geometry to one Fe(1), one Fe(3), and one P(4) atom. In the twelfth O site, O(12) is bonded in a distorted bent 150 degrees geometry to one Mn(1) and one P(4) atom.
MnFe3(PO4)4 crystallizes in the monoclinic Pm space group. Mn(1) is bonded to one O(12), one O(4), two equivalent O(2), and two equivalent O(8) atoms to form distorted MnO6 pentagonal pyramids that share corners with four equivalent Fe(2)O6 octahedra,  a cornercorner with one P(3)O4 tetrahedra,  a cornercorner with one P(4)O4 tetrahedra, corners with two equivalent P(1)O4 tetrahedra, and  an edgeedge with one P(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 49-50°. The Mn(1)-O(12) bond length is 1.91 Å. The Mn(1)-O(4) bond length is 1.90 Å. Both Mn(1)-O(2) bond lengths are 2.03 Å. Both Mn(1)-O(8) bond lengths are 2.35 Å. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(3), one O(7), two equivalent O(11), and two equivalent O(5) atoms to form distorted FeO6 octahedra that share corners with four equivalent Fe(3)O6 octahedra,  a cornercorner with one P(3)O4 tetrahedra,  a cornercorner with one P(4)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, and  an edgeedge with one P(4)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 48-49°. The Fe(1)-O(3) bond length is 1.95 Å. The Fe(1)-O(7) bond length is 1.93 Å. Both Fe(1)-O(11) bond lengths are 2.17 Å. Both Fe(1)-O(5) bond lengths are 2.09 Å. In the second Fe site, Fe(2) is bonded to one O(10), one O(6), two equivalent O(2), and two equivalent O(8) atoms to form distorted FeO6 octahedra that share corners with four equivalent Mn(1)O6 pentagonal pyramids,  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(2)O4 tetrahedra, corners with two equivalent P(3)O4 tetrahedra, and  an edgeedge with one P(1)O4 tetrahedra. The Fe(2)-O(10) bond length is 1.95 Å. The Fe(2)-O(6) bond length is 1.95 Å. Both Fe(2)-O(2) bond lengths are 2.17 Å. Both Fe(2)-O(8) bond lengths are 2.04 Å. In the third Fe site, Fe(3) is bonded to one O(1), one O(9), two equivalent O(11), and two equivalent O(5) atoms to form distorted FeO6 octahedra that share corners with four equivalent Fe(1)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(2)O4 tetrahedra, corners with two equivalent P(4)O4 tetrahedra, and  an edgeedge with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 48-49°. The Fe(3)-O(1) bond length is 1.94 Å. The Fe(3)-O(9) bond length is 1.93 Å. Both Fe(3)-O(11) bond lengths are 2.10 Å. Both Fe(3)-O(5) bond lengths are 2.16 Å. There are four inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(10), and two equivalent O(2) atoms to form PO4 tetrahedra that share  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one Fe(3)O6 octahedra, corners with two equivalent Mn(1)O6 pentagonal pyramids, and  an edgeedge with one Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 40-44°. The P(1)-O(1) bond length is 1.52 Å. The P(1)-O(10) bond length is 1.52 Å. Both P(1)-O(2) bond lengths are 1.58 Å. In the second P site, P(2) is bonded to one O(6), one O(9), and two equivalent O(5) atoms to form PO4 tetrahedra that share  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one Fe(3)O6 octahedra, corners with two equivalent Fe(1)O6 octahedra, and  an edgeedge with one Fe(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 42-56°. The P(2)-O(6) bond length is 1.53 Å. The P(2)-O(9) bond length is 1.53 Å. Both P(2)-O(5) bond lengths are 1.58 Å. In the third P site, P(3) is bonded to one O(4), one O(7), and two equivalent O(8) atoms to form PO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra,  a cornercorner with one Mn(1)O6 pentagonal pyramid, and  an edgeedge with one Mn(1)O6 pentagonal pyramid. The corner-sharing octahedral tilt angles range from 37-53°. The P(3)-O(4) bond length is 1.55 Å. The P(3)-O(7) bond length is 1.53 Å. Both P(3)-O(8) bond lengths are 1.56 Å. In the fourth P site, P(4) is bonded to one O(12), one O(3), and two equivalent O(11) atoms to form PO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra, corners with two equivalent Fe(3)O6 octahedra,  a cornercorner with one Mn(1)O6 pentagonal pyramid, and  an edgeedge with one Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 45-56°. The P(4)-O(12) bond length is 1.54 Å. The P(4)-O(3) bond length is 1.52 Å. Both P(4)-O(11) bond lengths are 1.58 Å. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Fe(3) and one P(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Mn(1), one Fe(2), and one P(1) atom. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to one Fe(1) and one P(4) atom. In the fourth O site, O(4) is bonded in a bent 120 degrees geometry to one Mn(1) and one P(3) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Fe(1), one Fe(3), and one P(2) atom. In the sixth O site, O(6) is bonded in a distorted bent 150 degrees geometry to one Fe(2) and one P(2) atom. In the seventh O site, O(7) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(3) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Mn(1), one Fe(2), and one P(3) atom. In the ninth O site, O(9) is bonded in a distorted bent 150 degrees geometry to one Fe(3) and one P(2) atom. In the tenth O site, O(10) is bonded in a distorted bent 150 degrees geometry to one Fe(2) and one P(1) atom. In the eleventh O site, O(11) is bonded in a distorted trigonal planar geometry to one Fe(1), one Fe(3), and one P(4) atom. In the twelfth O site, O(12) is bonded in a distorted bent 150 degrees geometry to one Mn(1) and one P(4) atom.