FeO2 is Hydrophilite-like structured and 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 50°. There are two inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to three equivalent Fe(1) atoms. In the second O site, O(2) is bonded in a distorted trigonal non-coplanar geometry to three equivalent Fe(1) atoms.
FeO2 is Hydrophilite-like structured and 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 50°. There are two shorter (1.94 Å) and one longer (1.97 Å) Fe(1)-O(1) bond length. There are two shorter (1.95 Å) and one longer (2.06 Å) Fe(1)-O(2) bond length. There are two inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to three equivalent Fe(1) atoms. In the second O site, O(2) is bonded in a distorted trigonal non-coplanar geometry to three equivalent Fe(1) atoms.