Fe4P5O23 crystallizes in the tetragonal I4_1/a space group. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(10), one O(11), one O(12), one O(3), one O(5), and one O(8) atom to form FeO6 octahedra that share  a cornercorner with one Fe(1)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(3)O4 tetrahedra, and corners with two equivalent P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 43-57°. The Fe(1)-O(10) bond length is 1.98 Å. The Fe(1)-O(11) bond length is 2.17 Å. The Fe(1)-O(12) bond length is 1.98 Å. The Fe(1)-O(3) bond length is 2.02 Å. The Fe(1)-O(5) bond length is 1.98 Å. The Fe(1)-O(8) bond length is 2.00 Å. In the second Fe site, Fe(2) is bonded to one O(1), one O(2), one O(6), one O(9), and two equivalent O(11) atoms to form FeO6 octahedra that share corners with two equivalent Fe(1)O6 octahedra,  a cornercorner with one P(2)O4 tetrahedra,  a cornercorner with one P(3)O4 tetrahedra, corners with two equivalent P(1)O4 tetrahedra, and  an edgeedge with one Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 54-57°. The Fe(2)-O(1) bond length is 1.97 Å. The Fe(2)-O(2) bond length is 1.98 Å. The Fe(2)-O(6) bond length is 1.93 Å. The Fe(2)-O(9) bond length is 1.97 Å. There is one shorter (2.15 Å) and one longer (2.16 Å) Fe(2)-O(11) bond length. There are three inequivalent P sites. In the first P site, 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  a cornercorner with one Fe(1)O6 octahedra and corners with two equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 51-56°. 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 1.54 Å. The P(1)-O(4) bond length is 1.53 Å. In the second P site, P(2) is bonded to one O(5), one O(6), one O(7), and one O(8) atom to form PO4 tetrahedra that share  a cornercorner with one Fe(2)O6 octahedra and corners with two equivalent Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 36-44°. The P(2)-O(5) bond length is 1.52 Å. The P(2)-O(6) bond length is 1.52 Å. The P(2)-O(7) bond length is 1.57 Å. The P(2)-O(8) bond length is 1.52 Å. In the third P site, P(3) is bonded to two equivalent O(10) and two equivalent O(9) atoms to form PO4 tetrahedra that share corners with two equivalent Fe(1)O6 octahedra and corners with two equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 51-56°. Both P(3)-O(10) bond lengths are 1.53 Å. Both P(3)-O(9) bond lengths are 1.53 Å. There are twelve inequivalent O sites. In the first O site, O(12) is bonded in a bent 150 degrees geometry to two equivalent Fe(1) atoms. In the second O site, O(1) is bonded in a bent 120 degrees geometry to one Fe(2) and one P(1) atom. In the third O site, O(2) is bonded in a bent 120 degrees geometry to one Fe(2) and one P(1) atom. In the fourth O site, O(3) is bonded in a bent 120 degrees geometry to one Fe(1) and one P(1) atom. In the fifth O site, O(4) is bonded in a single-bond geometry to one P(1) atom. In the sixth O site, O(5) is bonded in a distorted bent 150 degrees geometry to one Fe(1) and one P(2) atom. In the seventh O site, O(6) is bonded in a distorted bent 150 degrees geometry to one Fe(2) and one P(2) atom. In the eighth O site, O(7) is bonded in a single-bond geometry to one P(2) atom. In the ninth O site, O(8) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(2) atom. In the tenth O site, O(9) is bonded in a bent 120 degrees geometry to one Fe(2) and one P(3) atom. In the eleventh O site, O(10) is bonded in a bent 120 degrees geometry to one Fe(1) and one P(3) atom. In the twelfth O site, O(11) is bonded in a distorted trigonal planar geometry to one Fe(1) and two equivalent Fe(2) atoms. Linkers: 40 [O]P([O])([O])=O. Metal clusters: 32 [Fe]. The MOF has largest included sphere 9.61 A, density 1.44 g/cm3, surface area 2294.31 m2/g, accessible volume 0.45 cm3/g