MgFe2(NiO2)4 is Aluminum carbonitride-derived structured and crystallizes in the orthorhombic Imm2 space group. Mg(1) is bonded to two equivalent O(2) and two equivalent O(4) atoms to form distorted MgO4 tetrahedra that share corners with six equivalent Ni(2)O6 octahedra, corners with two equivalent Fe(1)O4 tetrahedra, and  an edgeedge with one Fe(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 37-64°. 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 FeO4 tetrahedra that share corners with six equivalent Ni(2)O6 octahedra and corners with two equivalent Mg(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 55-65°. In the second Fe site, Fe(2) is bonded to two equivalent O(1) and two equivalent O(4) atoms to form FeO4 tetrahedra that share corners with six equivalent Ni(2)O6 octahedra and  an edgeedge with one Mg(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 51-68°. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded in a 5-coordinate geometry to one O(3), two equivalent O(1), and two equivalent O(2) atoms. In the second Ni site, Ni(2) is bonded to one O(1), one O(2), two equivalent O(3), and two equivalent O(4) atoms to form NiO6 octahedra that share corners with three equivalent Mg(1)O4 tetrahedra, corners with three equivalent Fe(1)O4 tetrahedra, corners with three equivalent Fe(2)O4 tetrahedra, and edges with two equivalent Ni(2)O6 octahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Fe(2), one Ni(2), and two equivalent Ni(1) atoms to form OFeNi3 tetrahedra that share  a cornercorner with one O(1)FeNi3 tetrahedra, corners with four equivalent O(4)MgFeNi2 tetrahedra, and  an edgeedge with one O(1)FeNi3 tetrahedra. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Mg(1), one Fe(1), one Ni(2), and two equivalent Ni(1) atoms. In the third O site, O(3) is bonded in a rectangular see-saw-like geometry to one Fe(1), one Ni(1), and two equivalent Ni(2) atoms. In the fourth O site, O(4) is bonded to one Mg(1), one Fe(2), and two equivalent Ni(2) atoms to form distorted OMgFeNi2 tetrahedra that share corners with four equivalent O(1)FeNi3 tetrahedra and edges with two equivalent O(4)MgFeNi2 tetrahedra.
MgFe2(NiO2)4 is Aluminum carbonitride-derived structured and crystallizes in the orthorhombic Imm2 space group. Mg(1) is bonded to two equivalent O(2) and two equivalent O(4) atoms to form distorted MgO4 tetrahedra that share corners with six equivalent Ni(2)O6 octahedra, corners with two equivalent Fe(1)O4 tetrahedra, and  an edgeedge with one Fe(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 37-64°. Both Mg(1)-O(2) bond lengths are 1.98 Å. Both Mg(1)-O(4) bond lengths are 1.93 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 FeO4 tetrahedra that share corners with six equivalent Ni(2)O6 octahedra and corners with two equivalent Mg(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 55-65°. Both Fe(1)-O(2) bond lengths are 1.96 Å. Both Fe(1)-O(3) bond lengths are 1.94 Å. In the second Fe site, Fe(2) is bonded to two equivalent O(1) and two equivalent O(4) atoms to form FeO4 tetrahedra that share corners with six equivalent Ni(2)O6 octahedra and  an edgeedge with one Mg(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 51-68°. Both Fe(2)-O(1) bond lengths are 1.89 Å. Both Fe(2)-O(4) bond lengths are 1.98 Å. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded in a 5-coordinate geometry to one O(3), two equivalent O(1), and two equivalent O(2) atoms. The Ni(1)-O(3) bond length is 1.98 Å. Both Ni(1)-O(1) bond lengths are 2.00 Å. Both Ni(1)-O(2) bond lengths are 2.17 Å. In the second Ni site, Ni(2) is bonded to one O(1), one O(2), two equivalent O(3), and two equivalent O(4) atoms to form NiO6 octahedra that share corners with three equivalent Mg(1)O4 tetrahedra, corners with three equivalent Fe(1)O4 tetrahedra, corners with three equivalent Fe(2)O4 tetrahedra, and edges with two equivalent Ni(2)O6 octahedra. The Ni(2)-O(1) bond length is 2.11 Å. The Ni(2)-O(2) bond length is 2.24 Å. Both Ni(2)-O(3) bond lengths are 2.14 Å. Both Ni(2)-O(4) bond lengths are 2.12 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Fe(2), one Ni(2), and two equivalent Ni(1) atoms to form OFeNi3 tetrahedra that share  a cornercorner with one O(1)FeNi3 tetrahedra, corners with four equivalent O(4)MgFeNi2 tetrahedra, and  an edgeedge with one O(1)FeNi3 tetrahedra. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Mg(1), one Fe(1), one Ni(2), and two equivalent Ni(1) atoms. In the third O site, O(3) is bonded in a rectangular see-saw-like geometry to one Fe(1), one Ni(1), and two equivalent Ni(2) atoms. In the fourth O site, O(4) is bonded to one Mg(1), one Fe(2), and two equivalent Ni(2) atoms to form distorted OMgFeNi2 tetrahedra that share corners with four equivalent O(1)FeNi3 tetrahedra and edges with two equivalent O(4)MgFeNi2 tetrahedra.