Fe5O7 crystallizes in the monoclinic C2/m space group. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(1) and four equivalent O(3) atoms to form FeO6 octahedra that share corners with two equivalent Fe(3)O6 octahedra, corners with four equivalent Fe(2)O7 pentagonal bipyramids, edges with two equivalent Fe(1)O6 octahedra, and edges with six equivalent Fe(2)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 56°. In the second Fe site, Fe(2) is bonded to two equivalent O(1), two equivalent O(2), and three equivalent O(3) atoms to form distorted FeO7 pentagonal bipyramids that share corners with two equivalent Fe(1)O6 octahedra, corners with six equivalent Fe(3)O6 octahedra,  an edgeedge with one Fe(3)O6 octahedra, edges with three equivalent Fe(1)O6 octahedra, edges with two equivalent Fe(2)O7 pentagonal bipyramids, and faces with two equivalent Fe(2)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 19-68°. In the third Fe site, Fe(3) is bonded to one O(1), two equivalent O(4), and three equivalent O(2) atoms to form FeO6 octahedra that share  a cornercorner with one Fe(1)O6 octahedra, corners with two equivalent Fe(3)O6 octahedra, corners with six equivalent Fe(2)O7 pentagonal bipyramids, edges with five equivalent Fe(3)O6 octahedra, and  an edgeedge with one Fe(2)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles range from 0-56°. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Fe(1), one Fe(3), and two equivalent Fe(2) atoms to form distorted OFe4 tetrahedra that share corners with four equivalent O(3)Fe5 square pyramids, corners with three equivalent O(1)Fe4 tetrahedra, corners with five equivalent O(2)Fe5 trigonal bipyramids, edges with three equivalent O(3)Fe5 square pyramids, and  an edgeedge with one O(2)Fe5 trigonal bipyramid. In the second O site, O(2) is bonded to two equivalent Fe(2) and three equivalent Fe(3) atoms to form distorted OFe5 trigonal bipyramids that share corners with four equivalent O(3)Fe5 square pyramids, corners with five equivalent O(1)Fe4 tetrahedra,  an edgeedge with one O(3)Fe5 square pyramid,  an edgeedge with one O(1)Fe4 tetrahedra, and edges with four equivalent O(2)Fe5 trigonal bipyramids. In the third O site, O(3) is bonded to two equivalent Fe(1) and three equivalent Fe(2) atoms to form OFe5 square pyramids that share corners with two equivalent O(3)Fe5 square pyramids, corners with four equivalent O(1)Fe4 tetrahedra, corners with four equivalent O(2)Fe5 trigonal bipyramids, edges with five equivalent O(3)Fe5 square pyramids, edges with three equivalent O(1)Fe4 tetrahedra, and  an edgeedge with one O(2)Fe5 trigonal bipyramid. In the fourth O site, O(4) is bonded in a square co-planar geometry to four equivalent Fe(3) atoms.
Fe5O7 crystallizes in the monoclinic C2/m space group. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(1) and four equivalent O(3) atoms to form FeO6 octahedra that share corners with two equivalent Fe(3)O6 octahedra, corners with four equivalent Fe(2)O7 pentagonal bipyramids, edges with two equivalent Fe(1)O6 octahedra, and edges with six equivalent Fe(2)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 56°. Both Fe(1)-O(1) bond lengths are 2.03 Å. All Fe(1)-O(3) bond lengths are 2.05 Å. In the second Fe site, Fe(2) is bonded to two equivalent O(1), two equivalent O(2), and three equivalent O(3) atoms to form distorted FeO7 pentagonal bipyramids that share corners with two equivalent Fe(1)O6 octahedra, corners with six equivalent Fe(3)O6 octahedra,  an edgeedge with one Fe(3)O6 octahedra, edges with three equivalent Fe(1)O6 octahedra, edges with two equivalent Fe(2)O7 pentagonal bipyramids, and faces with two equivalent Fe(2)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 19-68°. Both Fe(2)-O(1) bond lengths are 2.07 Å. Both Fe(2)-O(2) bond lengths are 2.39 Å. There are two shorter (2.19 Å) and one longer (2.24 Å) Fe(2)-O(3) bond length. In the third Fe site, Fe(3) is bonded to one O(1), two equivalent O(4), and three equivalent O(2) atoms to form FeO6 octahedra that share  a cornercorner with one Fe(1)O6 octahedra, corners with two equivalent Fe(3)O6 octahedra, corners with six equivalent Fe(2)O7 pentagonal bipyramids, edges with five equivalent Fe(3)O6 octahedra, and  an edgeedge with one Fe(2)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles range from 0-56°. The Fe(3)-O(1) bond length is 1.99 Å. Both Fe(3)-O(4) bond lengths are 2.07 Å. There are two shorter (2.04 Å) and one longer (2.12 Å) Fe(3)-O(2) bond length. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Fe(1), one Fe(3), and two equivalent Fe(2) atoms to form distorted OFe4 tetrahedra that share corners with four equivalent O(3)Fe5 square pyramids, corners with three equivalent O(1)Fe4 tetrahedra, corners with five equivalent O(2)Fe5 trigonal bipyramids, edges with three equivalent O(3)Fe5 square pyramids, and  an edgeedge with one O(2)Fe5 trigonal bipyramid. In the second O site, O(2) is bonded to two equivalent Fe(2) and three equivalent Fe(3) atoms to form distorted OFe5 trigonal bipyramids that share corners with four equivalent O(3)Fe5 square pyramids, corners with five equivalent O(1)Fe4 tetrahedra,  an edgeedge with one O(3)Fe5 square pyramid,  an edgeedge with one O(1)Fe4 tetrahedra, and edges with four equivalent O(2)Fe5 trigonal bipyramids. In the third O site, O(3) is bonded to two equivalent Fe(1) and three equivalent Fe(2) atoms to form OFe5 square pyramids that share corners with two equivalent O(3)Fe5 square pyramids, corners with four equivalent O(1)Fe4 tetrahedra, corners with four equivalent O(2)Fe5 trigonal bipyramids, edges with five equivalent O(3)Fe5 square pyramids, edges with three equivalent O(1)Fe4 tetrahedra, and  an edgeedge with one O(2)Fe5 trigonal bipyramid. In the fourth O site, O(4) is bonded in a square co-planar geometry to four equivalent Fe(3) atoms.