Al5(CoO4)3 crystallizes in the monoclinic C2/m space group. There are three inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(3), one O(6), and two equivalent O(7) atoms to form CoO4 tetrahedra that share corners with three equivalent Al(4)O6 octahedra and corners with six equivalent Al(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 53-61°. In the second Co site, Co(2) is bonded to one O(2), one O(4), and two equivalent O(9) atoms to form CoO4 tetrahedra that share corners with two equivalent Al(3)O6 octahedra, corners with two equivalent Al(4)O6 octahedra, corners with three equivalent Al(1)O6 octahedra, and corners with four equivalent Al(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 55-61°. In the third Co site, Co(3) is bonded to one O(1), one O(5), and two equivalent O(8) atoms to form CoO4 tetrahedra that share  a cornercorner with one Al(4)O6 octahedra, corners with two equivalent Al(2)O6 octahedra, corners with three equivalent Al(1)O6 octahedra, and corners with four equivalent Al(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 52-61°. There are four inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(4), one O(5), two equivalent O(8), and two equivalent O(9) atoms to form AlO6 octahedra that share corners with three equivalent Co(2)O4 tetrahedra, corners with three equivalent Co(3)O4 tetrahedra,  an edgeedge with one Al(4)O6 octahedra, edges with two equivalent Al(2)O6 octahedra, and edges with two equivalent Al(3)O6 octahedra. In the second Al site, Al(2) is bonded to one O(1), one O(3), one O(4), one O(6), one O(7), and one O(9) atom to form AlO6 octahedra that share  a cornercorner with one Co(3)O4 tetrahedra, corners with two equivalent Co(2)O4 tetrahedra, corners with three equivalent Co(1)O4 tetrahedra,  an edgeedge with one Al(1)O6 octahedra, edges with two equivalent Al(2)O6 octahedra, and edges with two equivalent Al(4)O6 octahedra. In the third Al site, Al(3) is bonded to two equivalent O(2), two equivalent O(5), and two equivalent O(8) atoms to form AlO6 octahedra that share corners with two equivalent Co(2)O4 tetrahedra, corners with four equivalent Co(3)O4 tetrahedra, edges with two equivalent Al(1)O6 octahedra, and edges with two equivalent Al(3)O6 octahedra. In the fourth Al site, Al(4) is bonded to one O(1), one O(3), two equivalent O(7), and two equivalent O(9) atoms to form AlO6 octahedra that share  a cornercorner with one Co(3)O4 tetrahedra, corners with two equivalent Co(2)O4 tetrahedra, corners with three equivalent Co(1)O4 tetrahedra,  an edgeedge with one Al(1)O6 octahedra, and edges with four equivalent Al(2)O6 octahedra. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a rectangular see-saw-like geometry to one Co(3), one Al(4), and two equivalent Al(2) atoms. In the second O site, O(2) is bonded in a trigonal planar geometry to one Co(2) and two equivalent Al(3) atoms. In the third O site, O(3) is bonded to one Co(1), one Al(4), and two equivalent Al(2) atoms to form distorted edge-sharing OAl3Co tetrahedra. In the fourth O site, O(4) is bonded to one Co(2), one Al(1), and two equivalent Al(2) atoms to form a mixture of distorted corner and edge-sharing OAl3Co tetrahedra. In the fifth O site, O(5) is bonded in a rectangular see-saw-like geometry to one Co(3), one Al(1), and two equivalent Al(3) atoms. In the sixth O site, O(6) is bonded in a trigonal planar geometry to one Co(1) and two equivalent Al(2) atoms. In the seventh O site, O(7) is bonded in a trigonal planar geometry to one Co(1), one Al(2), and one Al(4) atom. In the eighth O site, O(8) is bonded in a trigonal planar geometry to one Co(3), one Al(1), and one Al(3) atom. In the ninth O site, O(9) is bonded to one Co(2), one Al(1), one Al(2), and one Al(4) atom to form a mixture of distorted corner and edge-sharing OAl3Co trigonal pyramids.
Al5(CoO4)3 crystallizes in the monoclinic C2/m space group. There are three inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(3), one O(6), and two equivalent O(7) atoms to form CoO4 tetrahedra that share corners with three equivalent Al(4)O6 octahedra and corners with six equivalent Al(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 53-61°. The Co(1)-O(3) bond length is 1.95 Å. The Co(1)-O(6) bond length is 1.85 Å. Both Co(1)-O(7) bond lengths are 1.86 Å. In the second Co site, Co(2) is bonded to one O(2), one O(4), and two equivalent O(9) atoms to form CoO4 tetrahedra that share corners with two equivalent Al(3)O6 octahedra, corners with two equivalent Al(4)O6 octahedra, corners with three equivalent Al(1)O6 octahedra, and corners with four equivalent Al(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 55-61°. The Co(2)-O(2) bond length is 1.82 Å. The Co(2)-O(4) bond length is 1.98 Å. Both Co(2)-O(9) bond lengths are 1.94 Å. In the third Co site, Co(3) is bonded to one O(1), one O(5), and two equivalent O(8) atoms to form CoO4 tetrahedra that share  a cornercorner with one Al(4)O6 octahedra, corners with two equivalent Al(2)O6 octahedra, corners with three equivalent Al(1)O6 octahedra, and corners with four equivalent Al(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 52-61°. The Co(3)-O(1) bond length is 1.98 Å. The Co(3)-O(5) bond length is 2.00 Å. Both Co(3)-O(8) bond lengths are 1.81 Å. There are four inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(4), one O(5), two equivalent O(8), and two equivalent O(9) atoms to form AlO6 octahedra that share corners with three equivalent Co(2)O4 tetrahedra, corners with three equivalent Co(3)O4 tetrahedra,  an edgeedge with one Al(4)O6 octahedra, edges with two equivalent Al(2)O6 octahedra, and edges with two equivalent Al(3)O6 octahedra. The Al(1)-O(4) bond length is 1.90 Å. The Al(1)-O(5) bond length is 1.98 Å. Both Al(1)-O(8) bond lengths are 1.87 Å. Both Al(1)-O(9) bond lengths are 1.94 Å. In the second Al site, Al(2) is bonded to one O(1), one O(3), one O(4), one O(6), one O(7), and one O(9) atom to form AlO6 octahedra that share  a cornercorner with one Co(3)O4 tetrahedra, corners with two equivalent Co(2)O4 tetrahedra, corners with three equivalent Co(1)O4 tetrahedra,  an edgeedge with one Al(1)O6 octahedra, edges with two equivalent Al(2)O6 octahedra, and edges with two equivalent Al(4)O6 octahedra. The Al(2)-O(1) bond length is 1.95 Å. The Al(2)-O(3) bond length is 1.93 Å. The Al(2)-O(4) bond length is 1.98 Å. The Al(2)-O(6) bond length is 1.87 Å. The Al(2)-O(7) bond length is 1.86 Å. The Al(2)-O(9) bond length is 1.99 Å. In the third Al site, Al(3) is bonded to two equivalent O(2), two equivalent O(5), and two equivalent O(8) atoms to form AlO6 octahedra that share corners with two equivalent Co(2)O4 tetrahedra, corners with four equivalent Co(3)O4 tetrahedra, edges with two equivalent Al(1)O6 octahedra, and edges with two equivalent Al(3)O6 octahedra. Both Al(3)-O(2) bond lengths are 1.93 Å. Both Al(3)-O(5) bond lengths are 1.92 Å. Both Al(3)-O(8) bond lengths are 1.93 Å. In the fourth Al site, Al(4) is bonded to one O(1), one O(3), two equivalent O(7), and two equivalent O(9) atoms to form AlO6 octahedra that share  a cornercorner with one Co(3)O4 tetrahedra, corners with two equivalent Co(2)O4 tetrahedra, corners with three equivalent Co(1)O4 tetrahedra,  an edgeedge with one Al(1)O6 octahedra, and edges with four equivalent Al(2)O6 octahedra. The Al(4)-O(1) bond length is 1.95 Å. The Al(4)-O(3) bond length is 1.95 Å. Both Al(4)-O(7) bond lengths are 1.87 Å. Both Al(4)-O(9) bond lengths are 1.96 Å. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a rectangular see-saw-like geometry to one Co(3), one Al(4), and two equivalent Al(2) atoms. In the second O site, O(2) is bonded in a trigonal planar geometry to one Co(2) and two equivalent Al(3) atoms. In the third O site, O(3) is bonded to one Co(1), one Al(4), and two equivalent Al(2) atoms to form distorted edge-sharing OAl3Co tetrahedra. In the fourth O site, O(4) is bonded to one Co(2), one Al(1), and two equivalent Al(2) atoms to form a mixture of distorted corner and edge-sharing OAl3Co tetrahedra. In the fifth O site, O(5) is bonded in a rectangular see-saw-like geometry to one Co(3), one Al(1), and two equivalent Al(3) atoms. In the sixth O site, O(6) is bonded in a trigonal planar geometry to one Co(1) and two equivalent Al(2) atoms. In the seventh O site, O(7) is bonded in a trigonal planar geometry to one Co(1), one Al(2), and one Al(4) atom. In the eighth O site, O(8) is bonded in a trigonal planar geometry to one Co(3), one Al(1), and one Al(3) atom. In the ninth O site, O(9) is bonded to one Co(2), one Al(1), one Al(2), and one Al(4) atom to form a mixture of distorted corner and edge-sharing OAl3Co trigonal pyramids.