Fe2P3O10 crystallizes in the monoclinic P2_1/m space group. Fe(1) is bonded to one O(3), one O(4), one O(5), one O(7), and two equivalent O(6) atoms to form FeO6 octahedra that share  a cornercorner with one P(1)O4 tetrahedra, corners with two equivalent P(3)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra, and edges with two equivalent Fe(1)O6 octahedra. There are three inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(2), and two equivalent O(4) atoms to form PO4 tetrahedra that share corners with two equivalent Fe(1)O6 octahedra,  a cornercorner with one P(2)O4 tetrahedra, and  a cornercorner with one P(3)O4 tetrahedra. The corner-sharing octahedral tilt angles are 24°. In the second P site, P(2) is bonded to one O(1), one O(3), and two equivalent O(6) atoms to form PO4 tetrahedra that share corners with six equivalent Fe(1)O6 octahedra and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 45-56°. In the third P site, P(3) is bonded to one O(2), one O(7), and two equivalent O(5) atoms to form PO4 tetrahedra that share corners with four equivalent Fe(1)O6 octahedra and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 47-55°. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one P(1) and one P(2) atom. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to one P(1) and one P(3) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to two equivalent Fe(1) and one P(2) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(1) atom. In the fifth O site, O(5) is bonded in a bent 120 degrees geometry to one Fe(1) and one P(3) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to two equivalent Fe(1) and one P(2) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to two equivalent Fe(1) and one P(3) atom.
Fe2P3O10 crystallizes in the monoclinic P2_1/m space group. Fe(1) is bonded to one O(3), one O(4), one O(5), one O(7), and two equivalent O(6) atoms to form FeO6 octahedra that share  a cornercorner with one P(1)O4 tetrahedra, corners with two equivalent P(3)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra, and edges with two equivalent Fe(1)O6 octahedra. The Fe(1)-O(3) bond length is 2.19 Å. The Fe(1)-O(4) bond length is 1.99 Å. The Fe(1)-O(5) bond length is 1.99 Å. The Fe(1)-O(7) bond length is 2.08 Å. There is one shorter (2.16 Å) and one longer (2.21 Å) Fe(1)-O(6) bond length. There are three inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(2), and two equivalent O(4) atoms to form PO4 tetrahedra that share corners with two equivalent Fe(1)O6 octahedra,  a cornercorner with one P(2)O4 tetrahedra, and  a cornercorner with one P(3)O4 tetrahedra. The corner-sharing octahedral tilt angles are 24°. The P(1)-O(1) bond length is 1.61 Å. The P(1)-O(2) bond length is 1.59 Å. Both P(1)-O(4) bond lengths are 1.50 Å. In the second P site, P(2) is bonded to one O(1), one O(3), and two equivalent O(6) atoms to form PO4 tetrahedra that share corners with six equivalent Fe(1)O6 octahedra and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 45-56°. The P(2)-O(1) bond length is 1.60 Å. The P(2)-O(3) bond length is 1.54 Å. Both P(2)-O(6) bond lengths are 1.55 Å. In the third P site, P(3) is bonded to one O(2), one O(7), and two equivalent O(5) atoms to form PO4 tetrahedra that share corners with four equivalent Fe(1)O6 octahedra and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 47-55°. The P(3)-O(2) bond length is 1.61 Å. The P(3)-O(7) bond length is 1.56 Å. Both P(3)-O(5) bond lengths are 1.52 Å. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one P(1) and one P(2) atom. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to one P(1) and one P(3) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to two equivalent Fe(1) and one P(2) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(1) atom. In the fifth O site, O(5) is bonded in a bent 120 degrees geometry to one Fe(1) and one P(3) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to two equivalent Fe(1) and one P(2) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to two equivalent Fe(1) and one P(3) atom.