MgFe2(HO2)2 crystallizes in the orthorhombic Amm2 space group. Mg(1) is bonded in a 3-coordinate geometry to one O(2) and two equivalent O(4) atoms. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form a mixture of distorted corner and edge-sharing FeO6 octahedra. The corner-sharing octahedral tilt angles are 12°. In the second Fe site, Fe(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form a mixture of corner and edge-sharing FeO6 octahedra. The corner-sharing octahedral tilt angles are 3°. H(1) is bonded in a 2-coordinate geometry to one O(3) and one O(4) atom. There are four inequivalent O sites. In the first O site, O(1) is bonded in a see-saw-like geometry to two equivalent Fe(1) and two equivalent Fe(2) atoms. In the second O site, O(2) is bonded to one Mg(1), two equivalent Fe(1), and two equivalent Fe(2) atoms to form corner-sharing OMgFe4 trigonal bipyramids. In the third O site, O(3) is bonded in a water-like geometry to two equivalent Fe(1) and two equivalent H(1) atoms. In the fourth O site, O(4) is bonded in a 6-coordinate geometry to two equivalent Mg(1), two equivalent Fe(2), and two equivalent H(1) atoms.
MgFe2(HO2)2 crystallizes in the orthorhombic Amm2 space group. Mg(1) is bonded in a 3-coordinate geometry to one O(2) and two equivalent O(4) atoms. The Mg(1)-O(2) bond length is 1.90 Å. Both Mg(1)-O(4) bond lengths are 2.00 Å. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form a mixture of distorted corner and edge-sharing FeO6 octahedra. The corner-sharing octahedral tilt angles are 12°. Both Fe(1)-O(1) bond lengths are 1.97 Å. Both Fe(1)-O(2) bond lengths are 2.25 Å. Both Fe(1)-O(3) bond lengths are 2.63 Å. In the second Fe site, Fe(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form a mixture of corner and edge-sharing FeO6 octahedra. The corner-sharing octahedral tilt angles are 3°. Both Fe(2)-O(1) bond lengths are 2.24 Å. Both Fe(2)-O(2) bond lengths are 2.14 Å. Both Fe(2)-O(4) bond lengths are 2.42 Å. H(1) is bonded in a 2-coordinate geometry to one O(3) and one O(4) atom. The H(1)-O(3) bond length is 1.04 Å. The H(1)-O(4) bond length is 1.54 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a see-saw-like geometry to two equivalent Fe(1) and two equivalent Fe(2) atoms. In the second O site, O(2) is bonded to one Mg(1), two equivalent Fe(1), and two equivalent Fe(2) atoms to form corner-sharing OMgFe4 trigonal bipyramids. In the third O site, O(3) is bonded in a water-like geometry to two equivalent Fe(1) and two equivalent H(1) atoms. In the fourth O site, O(4) is bonded in a 6-coordinate geometry to two equivalent Mg(1), two equivalent Fe(2), and two equivalent H(1) atoms.