MgFe2(HO2)2 crystallizes in the orthorhombic Amm2 space group. Mg(1) is bonded in a 6-coordinate geometry to two equivalent H(1), two equivalent O(1), 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(2) and two equivalent O(3) atoms to form corner-sharing FeO4 tetrahedra. In the second Fe site, Fe(2) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form corner-sharing FeO4 tetrahedra. H(1) is bonded in a distorted linear geometry to one Mg(1), one O(3), and one O(4) atom. There are four inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Mg(1) and two equivalent Fe(2) atoms to form distorted OMg2Fe2 trigonal pyramids that share corners with four equivalent O(2)Fe4 tetrahedra and corners with four equivalent O(1)Mg2Fe2 trigonal pyramids. In the second O site, O(2) is bonded to two equivalent Fe(1) and two equivalent Fe(2) atoms to form OFe4 tetrahedra that share corners with four equivalent O(3)Fe2H2 tetrahedra, corners with four equivalent O(2)Fe4 tetrahedra, and corners with four equivalent O(1)Mg2Fe2 trigonal pyramids. In the third O site, O(3) is bonded to two equivalent Fe(1) and two equivalent H(1) atoms to form distorted OFe2H2 tetrahedra that share corners with two equivalent O(3)Fe2H2 tetrahedra and corners with four equivalent O(2)Fe4 tetrahedra. In the fourth O site, O(4) is bonded in a distorted L-shaped geometry to two equivalent Mg(1) and two equivalent H(1) atoms.
MgFe2(HO2)2 crystallizes in the orthorhombic Amm2 space group. Mg(1) is bonded in a 6-coordinate geometry to two equivalent H(1), two equivalent O(1), and two equivalent O(4) atoms. Both Mg(1)-H(1) bond lengths are 1.96 Å. Both Mg(1)-O(1) bond lengths are 1.96 Å. Both Mg(1)-O(4) bond lengths are 2.11 Å. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(2) and two equivalent O(3) atoms to form corner-sharing FeO4 tetrahedra. Both Fe(1)-O(2) bond lengths are 2.09 Å. Both Fe(1)-O(3) bond lengths are 2.08 Å. In the second Fe site, Fe(2) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form corner-sharing FeO4 tetrahedra. Both Fe(2)-O(1) bond lengths are 2.08 Å. Both Fe(2)-O(2) bond lengths are 2.04 Å. H(1) is bonded in a distorted linear geometry to one Mg(1), one O(3), and one O(4) atom. The H(1)-O(3) bond length is 1.31 Å. The H(1)-O(4) bond length is 1.15 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Mg(1) and two equivalent Fe(2) atoms to form distorted OMg2Fe2 trigonal pyramids that share corners with four equivalent O(2)Fe4 tetrahedra and corners with four equivalent O(1)Mg2Fe2 trigonal pyramids. In the second O site, O(2) is bonded to two equivalent Fe(1) and two equivalent Fe(2) atoms to form OFe4 tetrahedra that share corners with four equivalent O(3)Fe2H2 tetrahedra, corners with four equivalent O(2)Fe4 tetrahedra, and corners with four equivalent O(1)Mg2Fe2 trigonal pyramids. In the third O site, O(3) is bonded to two equivalent Fe(1) and two equivalent H(1) atoms to form distorted OFe2H2 tetrahedra that share corners with two equivalent O(3)Fe2H2 tetrahedra and corners with four equivalent O(2)Fe4 tetrahedra. In the fourth O site, O(4) is bonded in a distorted L-shaped geometry to two equivalent Mg(1) and two equivalent H(1) atoms.