MgFe4(HO2)4 crystallizes in the tetragonal I4/m space group. Mg(1) is bonded in a distorted body-centered cubic geometry to eight equivalent H(1) atoms. 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 54°. H(1) is bonded in a single-bond geometry to two equivalent Mg(1) and one O(1) atom. There are two inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to three equivalent Fe(1) and one H(1) atom. In the second O site, O(2) is bonded in a trigonal planar geometry to three equivalent Fe(1) atoms.
MgFe4(HO2)4 crystallizes in the tetragonal I4/m space group. Mg(1) is bonded in a distorted body-centered cubic geometry to eight equivalent H(1) atoms. All Mg(1)-H(1) bond lengths are 2.46 Å. 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 54°. There is one shorter (2.15 Å) and two longer (2.16 Å) Fe(1)-O(1) bond lengths. All Fe(1)-O(2) bond lengths are 1.98 Å. H(1) is bonded in a single-bond geometry to two equivalent Mg(1) and one O(1) atom. The H(1)-O(1) bond length is 0.99 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to three equivalent Fe(1) and one H(1) atom. In the second O site, O(2) is bonded in a trigonal planar geometry to three equivalent Fe(1) atoms.