MgFe(CoO3)2 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(2), one O(5), two equivalent O(1), and two equivalent O(6) atoms to form MgO6 octahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Co(2)O6 octahedra, corners with four equivalent Co(1)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, and edges with two equivalent Co(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 5-23°. Fe(1) is bonded to one O(1), one O(5), two equivalent O(2), and two equivalent O(4) atoms to form FeO6 octahedra that share  a cornercorner with one Mg(1)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, and edges with two equivalent Co(2)O6 octahedra. The corner-sharing octahedral tilt angles are 23°. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(6) atoms to form CoO6 octahedra that share corners with four equivalent Mg(1)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, and edges with two equivalent Co(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 5-12°. In the second Co site, Co(2) is bonded to one O(2), one O(6), two equivalent O(3), and two equivalent O(5) atoms to form CoO6 octahedra that share  a cornercorner with one Mg(1)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, and edges with two equivalent Co(2)O6 octahedra. The corner-sharing octahedral tilt angles are 20°. There are six inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Mg(1), one Fe(1), and two equivalent Co(1) atoms to form OMg2FeCo2 square pyramids that share corners with four equivalent O(6)Mg2Co3 square pyramids, corners with three equivalent O(5)MgFeCo2 trigonal pyramids, edges with two equivalent O(6)Mg2Co3 square pyramids, and edges with two equivalent O(1)Mg2FeCo2 square pyramids. In the second O site, O(2) is bonded in a rectangular see-saw-like geometry to one Mg(1), two equivalent Fe(1), and one Co(2) atom. In the third O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one Co(1) and two equivalent Co(2) atoms. In the fourth O site, O(4) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Fe(1) and one Co(1) atom. In the fifth O site, O(5) is bonded to one Mg(1), one Fe(1), and two equivalent Co(2) atoms to form OMgFeCo2 trigonal pyramids that share corners with three equivalent O(1)Mg2FeCo2 square pyramids, corners with two equivalent O(5)MgFeCo2 trigonal pyramids, and edges with two equivalent O(6)Mg2Co3 square pyramids. In the sixth O site, O(6) is bonded to two equivalent Mg(1), one Co(2), and two equivalent Co(1) atoms to form OMg2Co3 square pyramids that share corners with four equivalent O(1)Mg2FeCo2 square pyramids, edges with two equivalent O(6)Mg2Co3 square pyramids, edges with two equivalent O(1)Mg2FeCo2 square pyramids, and edges with two equivalent O(5)MgFeCo2 trigonal pyramids.
MgFe(CoO3)2 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(2), one O(5), two equivalent O(1), and two equivalent O(6) atoms to form MgO6 octahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Co(2)O6 octahedra, corners with four equivalent Co(1)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, and edges with two equivalent Co(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 5-23°. The Mg(1)-O(2) bond length is 2.09 Å. The Mg(1)-O(5) bond length is 2.10 Å. There is one shorter (2.10 Å) and one longer (2.13 Å) Mg(1)-O(1) bond length. There is one shorter (2.12 Å) and one longer (2.15 Å) Mg(1)-O(6) bond length. Fe(1) is bonded to one O(1), one O(5), two equivalent O(2), and two equivalent O(4) atoms to form FeO6 octahedra that share  a cornercorner with one Mg(1)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, and edges with two equivalent Co(2)O6 octahedra. The corner-sharing octahedral tilt angles are 23°. The Fe(1)-O(1) bond length is 2.10 Å. The Fe(1)-O(5) bond length is 2.01 Å. There is one shorter (2.07 Å) and one longer (2.09 Å) Fe(1)-O(2) bond length. There is one shorter (1.96 Å) and one longer (1.97 Å) Fe(1)-O(4) bond length. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(6) atoms to form CoO6 octahedra that share corners with four equivalent Mg(1)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, and edges with two equivalent Co(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 5-12°. The Co(1)-O(3) bond length is 1.91 Å. The Co(1)-O(4) bond length is 1.86 Å. There is one shorter (1.97 Å) and one longer (2.20 Å) Co(1)-O(1) bond length. There is one shorter (1.98 Å) and one longer (2.21 Å) Co(1)-O(6) bond length. In the second Co site, Co(2) is bonded to one O(2), one O(6), two equivalent O(3), and two equivalent O(5) atoms to form CoO6 octahedra that share  a cornercorner with one Mg(1)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, and edges with two equivalent Co(2)O6 octahedra. The corner-sharing octahedral tilt angles are 20°. The Co(2)-O(2) bond length is 1.87 Å. The Co(2)-O(6) bond length is 1.90 Å. There is one shorter (1.90 Å) and one longer (1.93 Å) Co(2)-O(3) bond length. There is one shorter (1.95 Å) and one longer (1.96 Å) Co(2)-O(5) bond length. There are six inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Mg(1), one Fe(1), and two equivalent Co(1) atoms to form OMg2FeCo2 square pyramids that share corners with four equivalent O(6)Mg2Co3 square pyramids, corners with three equivalent O(5)MgFeCo2 trigonal pyramids, edges with two equivalent O(6)Mg2Co3 square pyramids, and edges with two equivalent O(1)Mg2FeCo2 square pyramids. In the second O site, O(2) is bonded in a rectangular see-saw-like geometry to one Mg(1), two equivalent Fe(1), and one Co(2) atom. In the third O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one Co(1) and two equivalent Co(2) atoms. In the fourth O site, O(4) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Fe(1) and one Co(1) atom. In the fifth O site, O(5) is bonded to one Mg(1), one Fe(1), and two equivalent Co(2) atoms to form OMgFeCo2 trigonal pyramids that share corners with three equivalent O(1)Mg2FeCo2 square pyramids, corners with two equivalent O(5)MgFeCo2 trigonal pyramids, and edges with two equivalent O(6)Mg2Co3 square pyramids. In the sixth O site, O(6) is bonded to two equivalent Mg(1), one Co(2), and two equivalent Co(1) atoms to form OMg2Co3 square pyramids that share corners with four equivalent O(1)Mg2FeCo2 square pyramids, edges with two equivalent O(6)Mg2Co3 square pyramids, edges with two equivalent O(1)Mg2FeCo2 square pyramids, and edges with two equivalent O(5)MgFeCo2 trigonal pyramids.