Fe(PO3)3 crystallizes in the orthorhombic Pccn space group. Fe(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form FeO6 octahedra that share corners with two equivalent P(1)O4 tetrahedra and corners with four equivalent P(2)O4 tetrahedra. There are two inequivalent P sites. In the first P site, P(1) is bonded to two equivalent O(1) and two equivalent O(4) atoms to form PO4 tetrahedra that share corners with two equivalent Fe(1)O6 octahedra and corners with two equivalent P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 35°. In the second P site, P(2) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form PO4 tetrahedra that share corners with two equivalent Fe(1)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra, and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 35-36°. There are five inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(1) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(2) 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 bent 150 degrees geometry to one P(1) and one P(2) atom. In the fifth O site, O(5) is bonded in a bent 120 degrees geometry to two equivalent P(2) atoms.
Fe(PO3)3 crystallizes in the orthorhombic Pccn space group. Fe(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form FeO6 octahedra that share corners with two equivalent P(1)O4 tetrahedra and corners with four equivalent P(2)O4 tetrahedra. Both Fe(1)-O(1) bond lengths are 1.94 Å. Both Fe(1)-O(2) bond lengths are 2.12 Å. Both Fe(1)-O(3) bond lengths are 2.01 Å. There are two inequivalent P sites. In the first P site, P(1) is bonded to two equivalent O(1) and two equivalent O(4) atoms to form PO4 tetrahedra that share corners with two equivalent Fe(1)O6 octahedra and corners with two equivalent P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 35°. Both P(1)-O(1) bond lengths are 1.50 Å. Both P(1)-O(4) bond lengths are 1.59 Å. In the second P site, P(2) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form PO4 tetrahedra that share corners with two equivalent Fe(1)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra, and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 35-36°. The P(2)-O(2) bond length is 1.50 Å. The P(2)-O(3) bond length is 1.50 Å. The P(2)-O(4) bond length is 1.61 Å. The P(2)-O(5) bond length is 1.62 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(1) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(2) 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 bent 150 degrees geometry to one P(1) and one P(2) atom. In the fifth O site, O(5) is bonded in a bent 120 degrees geometry to two equivalent P(2) atoms.