FeOOH crystallizes in the tetragonal I4/m space group. Fe(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form a mixture of distorted corner and edge-sharing FeO6 octahedra. The corner-sharing octahedral tilt angles are 53°. H(1) is bonded in a single-bond geometry to one O(1) atom. There are two inequivalent O sites. In the first O site, O(2) is bonded in a trigonal planar geometry to three equivalent Fe(1) atoms. In the second O site, O(1) is bonded in a distorted single-bond geometry to three equivalent Fe(1) and one H(1) atom.
FeOOH crystallizes in the tetragonal I4/m space group. Fe(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form a mixture of distorted corner and edge-sharing FeO6 octahedra. The corner-sharing octahedral tilt angles are 53°. There are two shorter (2.13 Å) and one longer (2.24 Å) Fe(1)-O(1) bond length. There is one shorter (1.94 Å) and two longer (1.97 Å) Fe(1)-O(2) bond lengths. H(1) is bonded in a single-bond geometry to one O(1) atom. The H(1)-O(1) bond length is 0.97 Å. There are two inequivalent O sites. In the first O site, O(2) is bonded in a trigonal planar geometry to three equivalent Fe(1) atoms. In the second O site, O(1) is bonded in a distorted single-bond geometry to three equivalent Fe(1) and one H(1) atom.