MgFe3(PO4)3 crystallizes in the triclinic P1 space group. Mg(1) is bonded in a 4-coordinate geometry to one O(11), one O(12), one O(2), and one O(8) atom. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(10), one O(3), one O(4), and one O(9) atom to form distorted 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 to one O(1), one O(11), one O(6), and one O(8) atom to form distorted FeO4 trigonal pyramids that share corners with two equivalent P(1)O4 tetrahedra and corners with two equivalent P(3)O4 tetrahedra. In the third Fe site, Fe(3) is bonded to one O(12), one O(2), one O(5), and one O(7) atom to form 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 one O(11), one O(12), one O(2), and one O(8) atom to form PO4 tetrahedra that share corners with two equivalent Fe(2)O4 trigonal pyramids and corners with two equivalent Fe(3)O4 trigonal pyramids. In the second P site, P(2) is bonded to one O(3), one O(4), one O(5), and one O(7) atom 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 one O(1), one O(10), one O(6), and one O(9) atom to form PO4 tetrahedra that share corners with two equivalent Fe(1)O4 tetrahedra and corners with two equivalent Fe(2)O4 trigonal pyramids. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 150 degrees geometry to one Fe(2) and one P(3) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Mg(1), one Fe(3), and one P(1) atom. In the third O site, O(3) is bonded in a linear 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(1) and one P(2) atom. In the fifth O site, O(5) is bonded in a bent 120 degrees geometry to 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(3) atom. In the seventh O site, O(7) is bonded in a bent 120 degrees geometry to one Fe(3) and one P(2) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Mg(1), one Fe(2), and one P(1) atom. In the ninth O site, O(9) is bonded in a linear geometry to one Fe(1) and one P(3) atom. In the tenth O site, O(10) is bonded in a linear geometry to one Fe(1) and one P(3) atom. In the eleventh O site, O(11) is bonded in a 3-coordinate geometry to one Mg(1), one Fe(2), and one P(1) atom. In the twelfth O site, O(12) is bonded in a 3-coordinate geometry to one Mg(1), one Fe(3), and one P(1) atom.
MgFe3(PO4)3 crystallizes in the triclinic P1 space group. Mg(1) is bonded in a 4-coordinate geometry to one O(11), one O(12), one O(2), and one O(8) atom. The Mg(1)-O(11) bond length is 2.12 Å. The Mg(1)-O(12) bond length is 2.09 Å. The Mg(1)-O(2) bond length is 2.09 Å. The Mg(1)-O(8) bond length is 2.12 Å. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(10), one O(3), one O(4), and one O(9) atom to form distorted FeO4 tetrahedra that share corners with two equivalent P(2)O4 tetrahedra and corners with two equivalent P(3)O4 tetrahedra. The Fe(1)-O(10) bond length is 1.87 Å. The Fe(1)-O(3) bond length is 1.88 Å. The Fe(1)-O(4) bond length is 1.88 Å. The Fe(1)-O(9) bond length is 1.87 Å. In the second Fe site, Fe(2) is bonded to one O(1), one O(11), one O(6), and one O(8) atom to form distorted FeO4 trigonal pyramids that share corners with two equivalent P(1)O4 tetrahedra and corners with two equivalent P(3)O4 tetrahedra. The Fe(2)-O(1) bond length is 1.91 Å. The Fe(2)-O(11) bond length is 2.11 Å. The Fe(2)-O(6) bond length is 1.91 Å. The Fe(2)-O(8) bond length is 2.11 Å. In the third Fe site, Fe(3) is bonded to one O(12), one O(2), one O(5), and one O(7) atom to form FeO4 trigonal pyramids that share corners with two equivalent P(1)O4 tetrahedra and corners with two equivalent P(2)O4 tetrahedra. The Fe(3)-O(12) bond length is 2.11 Å. The Fe(3)-O(2) bond length is 2.11 Å. The Fe(3)-O(5) bond length is 1.91 Å. The Fe(3)-O(7) bond length is 1.91 Å. There are three inequivalent P sites. In the first P site, P(1) is bonded to one O(11), one O(12), one O(2), and one O(8) atom to form PO4 tetrahedra that share corners with two equivalent Fe(2)O4 trigonal pyramids and corners with two equivalent Fe(3)O4 trigonal pyramids. The P(1)-O(11) bond length is 1.56 Å. The P(1)-O(12) bond length is 1.56 Å. The P(1)-O(2) bond length is 1.56 Å. The P(1)-O(8) bond length is 1.56 Å. In the second P site, P(2) is bonded to one O(3), one O(4), one O(5), and one O(7) atom to form PO4 tetrahedra that share corners with two equivalent Fe(1)O4 tetrahedra and corners with two equivalent Fe(3)O4 trigonal pyramids. The P(2)-O(3) bond length is 1.54 Å. The P(2)-O(4) bond length is 1.54 Å. The P(2)-O(5) bond length is 1.54 Å. The P(2)-O(7) bond length is 1.54 Å. In the third P site, P(3) is bonded to one O(1), one O(10), one O(6), and one O(9) atom to form PO4 tetrahedra that share corners with two equivalent Fe(1)O4 tetrahedra and corners with two equivalent Fe(2)O4 trigonal pyramids. The P(3)-O(1) bond length is 1.54 Å. The P(3)-O(10) bond length is 1.55 Å. The P(3)-O(6) bond length is 1.54 Å. The P(3)-O(9) bond length is 1.55 Å. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 150 degrees geometry to one Fe(2) and one P(3) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Mg(1), one Fe(3), and one P(1) atom. In the third O site, O(3) is bonded in a linear 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(1) and one P(2) atom. In the fifth O site, O(5) is bonded in a bent 120 degrees geometry to 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(3) atom. In the seventh O site, O(7) is bonded in a bent 120 degrees geometry to one Fe(3) and one P(2) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Mg(1), one Fe(2), and one P(1) atom. In the ninth O site, O(9) is bonded in a linear geometry to one Fe(1) and one P(3) atom. In the tenth O site, O(10) is bonded in a linear geometry to one Fe(1) and one P(3) atom. In the eleventh O site, O(11) is bonded in a 3-coordinate geometry to one Mg(1), one Fe(2), and one P(1) atom. In the twelfth O site, O(12) is bonded in a 3-coordinate geometry to one Mg(1), one Fe(3), and one P(1) atom.