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(3), one O(6), and one O(8) atom. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 5-coordinate geometry to one O(1), one O(11), one O(5), one O(6), and one O(9) atom. In the second Fe site, Fe(2) is bonded in a 5-coordinate geometry to one O(12), one O(2), one O(3), one O(4), and one O(8) atom. In the third Fe site, Fe(3) is bonded to one O(10), one O(2), one O(5), and one O(7) atom to form FeO4 tetrahedra 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(12), one O(2), one O(4), and one O(7) atom to form PO4 tetrahedra that share corners with two equivalent Fe(3)O4 tetrahedra. In the second P site, P(2) is bonded to one O(1), one O(10), one O(5), and one O(9) atom to form PO4 tetrahedra that share corners with two equivalent Fe(3)O4 tetrahedra. In the third P site, P(3) is bonded in a tetrahedral geometry to one O(11), one O(3), one O(6), and one O(8) atom. 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(1) and one P(2) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Fe(2), one Fe(3), 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 Fe(2), and one P(3) atom. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to one Fe(2) and one P(1) atom. In the fifth O site, O(5) is bonded in a 3-coordinate 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 trigonal planar geometry to one Mg(1), one Fe(1), and one P(3) atom. In the seventh O site, O(7) is bonded in a bent 150 degrees geometry to one Fe(3) and one P(1) atom. In the eighth O site, O(8) is bonded in a distorted T-shaped geometry to one Mg(1), one Fe(2), and one P(3) atom. In the ninth O site, O(9) is bonded in a water-like geometry to one Fe(1) and one P(2) atom. In the tenth O site, O(10) is bonded in a bent 150 degrees geometry to one Fe(3) and one P(2) atom. In the eleventh O site, O(11) is bonded in a distorted T-shaped geometry to one Mg(1), one Fe(1), and one P(3) atom. In the twelfth O site, O(12) is bonded in a water-like geometry to one Fe(2) 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(3), one O(6), and one O(8) atom. The Mg(1)-O(11) bond length is 2.07 Å. The Mg(1)-O(3) bond length is 2.05 Å. The Mg(1)-O(6) bond length is 2.05 Å. The Mg(1)-O(8) bond length is 2.08 Å. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 5-coordinate geometry to one O(1), one O(11), one O(5), one O(6), and one O(9) atom. The Fe(1)-O(1) bond length is 1.94 Å. The Fe(1)-O(11) bond length is 2.11 Å. The Fe(1)-O(5) bond length is 2.50 Å. The Fe(1)-O(6) bond length is 2.10 Å. The Fe(1)-O(9) bond length is 2.02 Å. In the second Fe site, Fe(2) is bonded in a 5-coordinate geometry to one O(12), one O(2), one O(3), one O(4), and one O(8) atom. The Fe(2)-O(12) bond length is 2.01 Å. The Fe(2)-O(2) bond length is 2.56 Å. The Fe(2)-O(3) bond length is 2.10 Å. The Fe(2)-O(4) bond length is 1.94 Å. The Fe(2)-O(8) bond length is 2.11 Å. In the third Fe site, Fe(3) is bonded to one O(10), one O(2), one O(5), and one O(7) atom to form FeO4 tetrahedra that share corners with two equivalent P(1)O4 tetrahedra and corners with two equivalent P(2)O4 tetrahedra. The Fe(3)-O(10) bond length is 1.88 Å. The Fe(3)-O(2) bond length is 1.91 Å. The Fe(3)-O(5) bond length is 1.91 Å. The Fe(3)-O(7) bond length is 1.88 Å. There are three inequivalent P sites. In the first P site, P(1) is bonded to one O(12), one O(2), one O(4), and one O(7) atom to form PO4 tetrahedra that share corners with two equivalent Fe(3)O4 tetrahedra. The P(1)-O(12) bond length is 1.55 Å. The P(1)-O(2) bond length is 1.58 Å. The P(1)-O(4) bond length is 1.53 Å. The P(1)-O(7) bond length is 1.55 Å. In the second P site, P(2) is bonded to one O(1), one O(10), one O(5), and one O(9) atom to form PO4 tetrahedra that share corners with two equivalent Fe(3)O4 tetrahedra. The P(2)-O(1) bond length is 1.53 Å. The P(2)-O(10) bond length is 1.55 Å. The P(2)-O(5) bond length is 1.58 Å. The P(2)-O(9) bond length is 1.55 Å. In the third P site, P(3) is bonded in a tetrahedral geometry to one O(11), one O(3), one O(6), and one O(8) atom. The P(3)-O(11) bond length is 1.55 Å. The P(3)-O(3) bond length is 1.56 Å. The P(3)-O(6) bond length is 1.56 Å. The P(3)-O(8) 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(1) and one P(2) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Fe(2), one Fe(3), 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 Fe(2), and one P(3) atom. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to one Fe(2) and one P(1) atom. In the fifth O site, O(5) is bonded in a 3-coordinate 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 trigonal planar geometry to one Mg(1), one Fe(1), and one P(3) atom. In the seventh O site, O(7) is bonded in a bent 150 degrees geometry to one Fe(3) and one P(1) atom. In the eighth O site, O(8) is bonded in a distorted T-shaped geometry to one Mg(1), one Fe(2), and one P(3) atom. In the ninth O site, O(9) is bonded in a water-like geometry to one Fe(1) and one P(2) atom. In the tenth O site, O(10) is bonded in a bent 150 degrees geometry to one Fe(3) and one P(2) atom. In the eleventh O site, O(11) is bonded in a distorted T-shaped geometry to one Mg(1), one Fe(1), and one P(3) atom. In the twelfth O site, O(12) is bonded in a water-like geometry to one Fe(2) and one P(1) atom.