MgFe3(PO4)3 crystallizes in the monoclinic P2 space group. Mg(1) is bonded in a 4-coordinate geometry to two equivalent O(1) and two equivalent O(5) atoms. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(3) and two equivalent O(6) atoms to form FeO4 tetrahedra that share corners with two equivalent P(2)O4 tetrahedra and corners with two equivalent P(3)O4 tetrahedra. In the second Fe site, Fe(2) is bonded in a distorted rectangular see-saw-like geometry to two equivalent O(1) and two equivalent O(5) atoms. In the third Fe site, Fe(3) is bonded to two equivalent O(2) and two equivalent O(4) atoms to form distorted FeO4 trigonal pyramids that share corners with two equivalent P(1)O4 tetrahedra and corners with two equivalent P(2)O4 tetrahedra. There are three inequivalent P sites. In the first P site, P(1) is bonded to two equivalent O(2) and two equivalent O(5) atoms to form PO4 tetrahedra that share corners with two equivalent Fe(3)O4 trigonal pyramids. In the second P site, P(2) is bonded to two equivalent O(3) and two equivalent O(4) atoms to form PO4 tetrahedra that share corners with two equivalent Fe(1)O4 tetrahedra and corners with two equivalent Fe(3)O4 trigonal pyramids. In the third P site, P(3) is bonded to two equivalent O(1) and two equivalent O(6) atoms to form PO4 tetrahedra that share corners with two equivalent Fe(1)O4 tetrahedra. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Mg(1), one Fe(2), and one P(3) atom. In the second O site, O(2) is bonded in a distorted linear geometry to one Fe(3) and one P(1) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(2) atom. In the fourth O site, O(4) is bonded in a linear geometry to one Fe(3) and one P(2) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Mg(1), one Fe(2), and one P(1) atom. In the sixth O site, O(6) is bonded in a linear geometry to one Fe(1) and one P(3) atom.
MgFe3(PO4)3 crystallizes in the monoclinic P2 space group. Mg(1) is bonded in a 4-coordinate geometry to two equivalent O(1) and two equivalent O(5) atoms. Both Mg(1)-O(1) bond lengths are 1.98 Å. Both Mg(1)-O(5) bond lengths are 1.95 Å. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(3) and two equivalent O(6) atoms to form FeO4 tetrahedra that share corners with two equivalent P(2)O4 tetrahedra and corners with two equivalent P(3)O4 tetrahedra. Both Fe(1)-O(3) bond lengths are 1.84 Å. Both Fe(1)-O(6) bond lengths are 1.94 Å. In the second Fe site, Fe(2) is bonded in a distorted rectangular see-saw-like geometry to two equivalent O(1) and two equivalent O(5) atoms. Both Fe(2)-O(1) bond lengths are 2.04 Å. Both Fe(2)-O(5) bond lengths are 1.97 Å. In the third Fe site, Fe(3) is bonded to two equivalent O(2) and two equivalent O(4) atoms to form distorted FeO4 trigonal pyramids that share corners with two equivalent P(1)O4 tetrahedra and corners with two equivalent P(2)O4 tetrahedra. Both Fe(3)-O(2) bond lengths are 2.06 Å. Both Fe(3)-O(4) bond lengths are 1.96 Å. There are three inequivalent P sites. In the first P site, P(1) is bonded to two equivalent O(2) and two equivalent O(5) atoms to form PO4 tetrahedra that share corners with two equivalent Fe(3)O4 trigonal pyramids. Both P(1)-O(2) bond lengths are 1.51 Å. Both P(1)-O(5) bond lengths are 1.60 Å. In the second P site, P(2) is bonded to two equivalent O(3) and two equivalent O(4) atoms to form PO4 tetrahedra that share corners with two equivalent Fe(1)O4 tetrahedra and corners with two equivalent Fe(3)O4 trigonal pyramids. Both P(2)-O(3) bond lengths are 1.58 Å. Both P(2)-O(4) bond lengths are 1.51 Å. In the third P site, P(3) is bonded to two equivalent O(1) and two equivalent O(6) atoms to form PO4 tetrahedra that share corners with two equivalent Fe(1)O4 tetrahedra. Both P(3)-O(1) bond lengths are 1.57 Å. Both P(3)-O(6) bond lengths are 1.52 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Mg(1), one Fe(2), and one P(3) atom. In the second O site, O(2) is bonded in a distorted linear geometry to one Fe(3) and one P(1) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(2) atom. In the fourth O site, O(4) is bonded in a linear geometry to one Fe(3) and one P(2) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Mg(1), one Fe(2), and one P(1) atom. In the sixth O site, O(6) is bonded in a linear geometry to one Fe(1) and one P(3) atom.