Fe3P2(HO5)2 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(3), two equivalent O(4), and two equivalent O(5) atoms to form distorted FeO6 octahedra that share corners with two equivalent Fe(2)O6 octahedra, corners with four equivalent P(1)O4 tetrahedra, and faces with two equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles are 56°. In the second Fe site, Fe(2) is bonded to one O(1), one O(2), one O(3), one O(4), and two equivalent O(5) atoms to form FeO6 octahedra that share  a cornercorner with one Fe(1)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra, corners with four equivalent P(1)O4 tetrahedra, and  a faceface with one Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 50-56°. P(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form PO4 tetrahedra that share corners with two equivalent Fe(1)O6 octahedra and corners with four equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 35-45°. H(1) is bonded in a single-bond geometry to one O(5) atom. There are five inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Fe(2) and one P(1) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Fe(2) and one P(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Fe(1), one Fe(2), and one P(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Fe(1), one Fe(2), and one P(1) atom. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to one Fe(1), two equivalent Fe(2), and one H(1) atom.
Fe3P2(HO5)2 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(3), two equivalent O(4), and two equivalent O(5) atoms to form distorted FeO6 octahedra that share corners with two equivalent Fe(2)O6 octahedra, corners with four equivalent P(1)O4 tetrahedra, and faces with two equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles are 56°. Both Fe(1)-O(3) bond lengths are 2.09 Å. Both Fe(1)-O(4) bond lengths are 2.21 Å. Both Fe(1)-O(5) bond lengths are 2.13 Å. In the second Fe site, Fe(2) is bonded to one O(1), one O(2), one O(3), one O(4), and two equivalent O(5) atoms to form FeO6 octahedra that share  a cornercorner with one Fe(1)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra, corners with four equivalent P(1)O4 tetrahedra, and  a faceface with one Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 50-56°. The Fe(2)-O(1) bond length is 1.96 Å. The Fe(2)-O(2) bond length is 1.95 Å. The Fe(2)-O(3) bond length is 2.09 Å. The Fe(2)-O(4) bond length is 2.06 Å. There is one shorter (2.07 Å) and one longer (2.15 Å) Fe(2)-O(5) bond length. P(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form PO4 tetrahedra that share corners with two equivalent Fe(1)O6 octahedra and corners with four equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 35-45°. The P(1)-O(1) bond length is 1.55 Å. The P(1)-O(2) bond length is 1.54 Å. The P(1)-O(3) bond length is 1.56 Å. The P(1)-O(4) bond length is 1.56 Å. H(1) is bonded in a single-bond geometry to one O(5) atom. The H(1)-O(5) bond length is 0.99 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(2) and one P(1) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Fe(2) and one P(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Fe(1), one Fe(2), and one P(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Fe(1), one Fe(2), and one P(1) atom. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to one Fe(1), two equivalent Fe(2), and one H(1) atom.