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 corner and edge-sharing FeO6 octahedra. The corner-sharing octahedral tilt angles are 46°. H(1) is bonded in a single-bond geometry to one O(2) atom. There are two inequivalent O sites. In the first O site, O(2) is bonded in a single-bond geometry to three equivalent Fe(1) and one H(1) atom. In the second O site, O(1) is bonded in a distorted trigonal non-coplanar geometry to three equivalent Fe(1) atoms.
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 corner and edge-sharing FeO6 octahedra. The corner-sharing octahedral tilt angles are 46°. There are two shorter (1.99 Å) and one longer (2.01 Å) Fe(1)-O(1) bond length. There is one shorter (2.11 Å) and two longer (2.16 Å) Fe(1)-O(2) bond lengths. H(1) is bonded in a single-bond geometry to one O(2) atom. The H(1)-O(2) bond length is 0.99 Å. There are two inequivalent O sites. In the first O site, O(2) is bonded in a single-bond geometry to three equivalent Fe(1) and one H(1) atom. In the second O site, O(1) is bonded in a distorted trigonal non-coplanar geometry to three equivalent Fe(1) atoms.