Fe5HO8 crystallizes in the orthorhombic Cmc2_1 space group. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(2), two equivalent O(4), and two equivalent O(6) atoms to form FeO6 octahedra that share corners with two equivalent Fe(3)O6 octahedra, corners with three equivalent Fe(4)O4 tetrahedra,  an edgeedge with one Fe(3)O6 octahedra, and edges with four equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles are 50°. In the second Fe site, Fe(2) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form FeO6 octahedra that share corners with two equivalent Fe(3)O6 octahedra, corners with three equivalent Fe(4)O4 tetrahedra,  an edgeedge with one Fe(3)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, and edges with two equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 52-55°. In the third Fe site, Fe(3) is bonded to one O(3), one O(5), two equivalent O(4), and two equivalent O(6) atoms to form FeO6 octahedra that share corners with two equivalent Fe(1)O6 octahedra, corners with four equivalent Fe(2)O6 octahedra, corners with three equivalent Fe(4)O4 tetrahedra,  an edgeedge with one Fe(1)O6 octahedra, and edges with two equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 50-55°. In the fourth Fe site, Fe(4) is bonded to one O(2), one O(5), and two equivalent O(6) atoms to form corner-sharing FeO4 tetrahedra. The corner-sharing octahedral tilt angles range from 54-64°. H(1) is bonded in a single-bond geometry to one O(1) atom. There are six inequivalent O sites. In the first O site, O(5) is bonded in a distorted rectangular see-saw-like geometry to one Fe(3), one Fe(4), and two equivalent Fe(2) atoms. In the second O site, O(6) is bonded to one Fe(1), one Fe(2), one Fe(3), and one Fe(4) atom to form a mixture of distorted edge and corner-sharing OFe4 tetrahedra. In the third O site, O(1) is bonded in a distorted single-bond geometry to one Fe(1), two equivalent Fe(2), and one H(1) atom. In the fourth O site, O(2) is bonded to one Fe(1), one Fe(4), and two equivalent Fe(2) atoms to form a mixture of distorted edge and corner-sharing OFe4 trigonal pyramids. In the fifth O site, O(3) is bonded in a trigonal planar geometry to one Fe(3) and two equivalent Fe(2) atoms. In the sixth O site, O(4) is bonded in a trigonal planar geometry to one Fe(1), one Fe(2), and one Fe(3) atom.
Fe5HO8 crystallizes in the orthorhombic Cmc2_1 space group. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(2), two equivalent O(4), and two equivalent O(6) atoms to form FeO6 octahedra that share corners with two equivalent Fe(3)O6 octahedra, corners with three equivalent Fe(4)O4 tetrahedra,  an edgeedge with one Fe(3)O6 octahedra, and edges with four equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles are 50°. The Fe(1)-O(1) bond length is 2.01 Å. The Fe(1)-O(2) bond length is 2.02 Å. Both Fe(1)-O(4) bond lengths are 1.93 Å. Both Fe(1)-O(6) bond lengths are 2.00 Å. In the second Fe site, Fe(2) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form FeO6 octahedra that share corners with two equivalent Fe(3)O6 octahedra, corners with three equivalent Fe(4)O4 tetrahedra,  an edgeedge with one Fe(3)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, and edges with two equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 52-55°. The Fe(2)-O(1) bond length is 2.07 Å. The Fe(2)-O(2) bond length is 2.02 Å. The Fe(2)-O(3) bond length is 1.97 Å. The Fe(2)-O(4) bond length is 1.98 Å. The Fe(2)-O(5) bond length is 2.09 Å. The Fe(2)-O(6) bond length is 2.08 Å. In the third Fe site, Fe(3) is bonded to one O(3), one O(5), two equivalent O(4), and two equivalent O(6) atoms to form FeO6 octahedra that share corners with two equivalent Fe(1)O6 octahedra, corners with four equivalent Fe(2)O6 octahedra, corners with three equivalent Fe(4)O4 tetrahedra,  an edgeedge with one Fe(1)O6 octahedra, and edges with two equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 50-55°. The Fe(3)-O(3) bond length is 1.97 Å. The Fe(3)-O(5) bond length is 2.13 Å. Both Fe(3)-O(4) bond lengths are 2.01 Å. Both Fe(3)-O(6) bond lengths are 2.15 Å. In the fourth Fe site, Fe(4) is bonded to one O(2), one O(5), and two equivalent O(6) atoms to form corner-sharing FeO4 tetrahedra. The corner-sharing octahedral tilt angles range from 54-64°. The Fe(4)-O(2) bond length is 1.93 Å. The Fe(4)-O(5) bond length is 1.91 Å. Both Fe(4)-O(6) bond lengths are 1.93 Å. H(1) is bonded in a single-bond geometry to one O(1) atom. The H(1)-O(1) bond length is 0.99 Å. There are six inequivalent O sites. In the first O site, O(5) is bonded in a distorted rectangular see-saw-like geometry to one Fe(3), one Fe(4), and two equivalent Fe(2) atoms. In the second O site, O(6) is bonded to one Fe(1), one Fe(2), one Fe(3), and one Fe(4) atom to form a mixture of distorted edge and corner-sharing OFe4 tetrahedra. In the third O site, O(1) is bonded in a distorted single-bond geometry to one Fe(1), two equivalent Fe(2), and one H(1) atom. In the fourth O site, O(2) is bonded to one Fe(1), one Fe(4), and two equivalent Fe(2) atoms to form a mixture of distorted edge and corner-sharing OFe4 trigonal pyramids. In the fifth O site, O(3) is bonded in a trigonal planar geometry to one Fe(3) and two equivalent Fe(2) atoms. In the sixth O site, O(4) is bonded in a trigonal planar geometry to one Fe(1), one Fe(2), and one Fe(3) atom.