Fe7(CoO6)2 is Spinel-like structured and crystallizes in the monoclinic C2/c space group. There are five inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(2), one O(4), and one O(6) atom to form FeO4 tetrahedra that share corners with two equivalent Fe(3)O6 octahedra, corners with two equivalent Fe(4)O6 octahedra, corners with four equivalent Fe(5)O6 octahedra, and corners with four equivalent Co(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 53-60°. In the second Fe site, Fe(2) is bonded to two equivalent O(3) and two equivalent O(5) atoms to form FeO4 tetrahedra that share corners with two equivalent Fe(3)O6 octahedra, corners with two equivalent Fe(4)O6 octahedra, corners with four equivalent Fe(5)O6 octahedra, and corners with four equivalent Co(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 54-59°. In the third Fe site, Fe(3) is bonded to two equivalent O(2), two equivalent O(5), and two equivalent O(6) atoms to form FeO6 octahedra that share corners with two equivalent Fe(2)O4 tetrahedra, corners with four equivalent Fe(1)O4 tetrahedra, edges with two equivalent Fe(4)O6 octahedra, edges with two equivalent Fe(5)O6 octahedra, and edges with two equivalent Co(1)O6 octahedra. In the fourth Fe site, Fe(4) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(6) atoms to form FeO6 octahedra that share corners with two equivalent Fe(2)O4 tetrahedra, corners with four equivalent Fe(1)O4 tetrahedra, edges with two equivalent Fe(3)O6 octahedra, edges with two equivalent Fe(5)O6 octahedra, and edges with two equivalent Co(1)O6 octahedra. In the fifth Fe site, Fe(5) is bonded to one O(2), one O(3), one O(4), one O(5), and two equivalent O(1) atoms to form FeO6 octahedra that share corners with two equivalent Fe(2)O4 tetrahedra, corners with four equivalent Fe(1)O4 tetrahedra,  an edgeedge with one Fe(3)O6 octahedra,  an edgeedge with one Fe(4)O6 octahedra,  an edgeedge with one Fe(5)O6 octahedra, and edges with three equivalent Co(1)O6 octahedra. Co(1) is bonded to one O(1), one O(3), one O(5), one O(6), and two equivalent O(4) atoms to form CoO6 octahedra that share corners with two equivalent Fe(2)O4 tetrahedra, corners with four equivalent Fe(1)O4 tetrahedra,  an edgeedge with one Fe(3)O6 octahedra,  an edgeedge with one Fe(4)O6 octahedra,  an edgeedge with one Co(1)O6 octahedra, and edges with three equivalent Fe(5)O6 octahedra. There are six inequivalent O sites. In the first O site, O(1) is bonded in a rectangular see-saw-like geometry to one Fe(1), two equivalent Fe(5), and one Co(1) atom. In the second O site, O(2) is bonded to one Fe(1), one Fe(3), one Fe(4), and one Fe(5) atom to form distorted corner-sharing OFe4 trigonal pyramids. In the third O site, O(3) is bonded in a rectangular see-saw-like geometry to one Fe(2), one Fe(4), one Fe(5), and one Co(1) atom. In the fourth O site, O(4) is bonded in a rectangular see-saw-like geometry to one Fe(1), one Fe(5), and two equivalent Co(1) atoms. In the fifth O site, O(5) is bonded in a rectangular see-saw-like geometry to one Fe(2), one Fe(3), one Fe(5), and one Co(1) atom. In the sixth O site, O(6) is bonded in a rectangular see-saw-like geometry to one Fe(1), one Fe(3), one Fe(4), and one Co(1) atom.
Fe7(CoO6)2 is Spinel-like structured and crystallizes in the monoclinic C2/c space group. There are five inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(2), one O(4), and one O(6) atom to form FeO4 tetrahedra that share corners with two equivalent Fe(3)O6 octahedra, corners with two equivalent Fe(4)O6 octahedra, corners with four equivalent Fe(5)O6 octahedra, and corners with four equivalent Co(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 53-60°. The Fe(1)-O(1) bond length is 1.91 Å. The Fe(1)-O(2) bond length is 1.96 Å. The Fe(1)-O(4) bond length is 1.90 Å. The Fe(1)-O(6) bond length is 1.95 Å. In the second Fe site, Fe(2) is bonded to two equivalent O(3) and two equivalent O(5) atoms to form FeO4 tetrahedra that share corners with two equivalent Fe(3)O6 octahedra, corners with two equivalent Fe(4)O6 octahedra, corners with four equivalent Fe(5)O6 octahedra, and corners with four equivalent Co(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 54-59°. Both Fe(2)-O(3) bond lengths are 1.94 Å. Both Fe(2)-O(5) bond lengths are 1.94 Å. In the third Fe site, Fe(3) is bonded to two equivalent O(2), two equivalent O(5), and two equivalent O(6) atoms to form FeO6 octahedra that share corners with two equivalent Fe(2)O4 tetrahedra, corners with four equivalent Fe(1)O4 tetrahedra, edges with two equivalent Fe(4)O6 octahedra, edges with two equivalent Fe(5)O6 octahedra, and edges with two equivalent Co(1)O6 octahedra. Both Fe(3)-O(2) bond lengths are 2.06 Å. Both Fe(3)-O(5) bond lengths are 2.05 Å. Both Fe(3)-O(6) bond lengths are 2.04 Å. In the fourth Fe site, Fe(4) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(6) atoms to form FeO6 octahedra that share corners with two equivalent Fe(2)O4 tetrahedra, corners with four equivalent Fe(1)O4 tetrahedra, edges with two equivalent Fe(3)O6 octahedra, edges with two equivalent Fe(5)O6 octahedra, and edges with two equivalent Co(1)O6 octahedra. Both Fe(4)-O(2) bond lengths are 2.06 Å. Both Fe(4)-O(3) bond lengths are 2.06 Å. Both Fe(4)-O(6) bond lengths are 2.05 Å. In the fifth Fe site, Fe(5) is bonded to one O(2), one O(3), one O(4), one O(5), and two equivalent O(1) atoms to form FeO6 octahedra that share corners with two equivalent Fe(2)O4 tetrahedra, corners with four equivalent Fe(1)O4 tetrahedra,  an edgeedge with one Fe(3)O6 octahedra,  an edgeedge with one Fe(4)O6 octahedra,  an edgeedge with one Fe(5)O6 octahedra, and edges with three equivalent Co(1)O6 octahedra. The Fe(5)-O(2) bond length is 2.16 Å. The Fe(5)-O(3) bond length is 2.11 Å. The Fe(5)-O(4) bond length is 2.05 Å. The Fe(5)-O(5) bond length is 2.09 Å. There is one shorter (2.06 Å) and one longer (2.07 Å) Fe(5)-O(1) bond length. Co(1) is bonded to one O(1), one O(3), one O(5), one O(6), and two equivalent O(4) atoms to form CoO6 octahedra that share corners with two equivalent Fe(2)O4 tetrahedra, corners with four equivalent Fe(1)O4 tetrahedra,  an edgeedge with one Fe(3)O6 octahedra,  an edgeedge with one Fe(4)O6 octahedra,  an edgeedge with one Co(1)O6 octahedra, and edges with three equivalent Fe(5)O6 octahedra. The Co(1)-O(1) bond length is 2.12 Å. The Co(1)-O(3) bond length is 2.09 Å. The Co(1)-O(5) bond length is 2.11 Å. The Co(1)-O(6) bond length is 2.13 Å. There is one shorter (2.09 Å) and one longer (2.12 Å) Co(1)-O(4) bond length. There are six inequivalent O sites. In the first O site, O(1) is bonded in a rectangular see-saw-like geometry to one Fe(1), two equivalent Fe(5), and one Co(1) atom. In the second O site, O(2) is bonded to one Fe(1), one Fe(3), one Fe(4), and one Fe(5) atom to form distorted corner-sharing OFe4 trigonal pyramids. In the third O site, O(3) is bonded in a rectangular see-saw-like geometry to one Fe(2), one Fe(4), one Fe(5), and one Co(1) atom. In the fourth O site, O(4) is bonded in a rectangular see-saw-like geometry to one Fe(1), one Fe(5), and two equivalent Co(1) atoms. In the fifth O site, O(5) is bonded in a rectangular see-saw-like geometry to one Fe(2), one Fe(3), one Fe(5), and one Co(1) atom. In the sixth O site, O(6) is bonded in a rectangular see-saw-like geometry to one Fe(1), one Fe(3), one Fe(4), and one Co(1) atom.