Co(SO4)2 crystallizes in the trigonal R3 space group. There are three inequivalent Co sites. In the first Co site, Co(1) is bonded to three equivalent O(2) and three equivalent O(6) atoms to form CoO6 octahedra that share corners with three equivalent S(1)O4 tetrahedra and corners with three equivalent S(2)O4 tetrahedra. In the second Co site, Co(2) is bonded to three equivalent O(7) and three equivalent O(8) atoms to form CoO6 octahedra that share corners with three equivalent S(1)O4 tetrahedra and corners with three equivalent S(2)O4 tetrahedra. In the third Co site, Co(3) is bonded to three equivalent O(3) and three equivalent O(5) atoms to form CoO6 octahedra that share corners with three equivalent S(1)O4 tetrahedra and corners with three equivalent S(2)O4 tetrahedra. There are two inequivalent S sites. In the first S site, S(1) is bonded to one O(2), one O(3), one O(4), and one O(8) atom to form SO4 tetrahedra that share  a cornercorner with one Co(1)O6 octahedra,  a cornercorner with one Co(2)O6 octahedra, and  a cornercorner with one Co(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 28-39°. In the second S site, S(2) is bonded to one O(1), one O(5), one O(6), and one O(7) atom to form SO4 tetrahedra that share  a cornercorner with one Co(1)O6 octahedra,  a cornercorner with one Co(2)O6 octahedra, and  a cornercorner with one Co(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 33-44°. There are eight inequivalent O sites. In the first O site, O(4) is bonded in a single-bond geometry to one S(1) atom. In the second O site, O(5) is bonded in a bent 150 degrees geometry to one Co(3) and one S(2) atom. In the third O site, O(6) is bonded in a bent 150 degrees geometry to one Co(1) and one S(2) atom. In the fourth O site, O(7) is bonded in a distorted bent 150 degrees geometry to one Co(2) and one S(2) atom. In the fifth O site, O(8) is bonded in a bent 150 degrees geometry to one Co(2) and one S(1) atom. In the sixth O site, O(1) is bonded in a single-bond geometry to one S(2) atom. In the seventh O site, O(2) is bonded in a bent 150 degrees geometry to one Co(1) and one S(1) atom. In the eighth O site, O(3) is bonded in a bent 150 degrees geometry to one Co(3) and one S(1) atom.
Co(SO4)2 crystallizes in the trigonal R3 space group. There are three inequivalent Co sites. In the first Co site, Co(1) is bonded to three equivalent O(2) and three equivalent O(6) atoms to form CoO6 octahedra that share corners with three equivalent S(1)O4 tetrahedra and corners with three equivalent S(2)O4 tetrahedra. All Co(1)-O(2) bond lengths are 2.00 Å. All Co(1)-O(6) bond lengths are 2.06 Å. In the second Co site, Co(2) is bonded to three equivalent O(7) and three equivalent O(8) atoms to form CoO6 octahedra that share corners with three equivalent S(1)O4 tetrahedra and corners with three equivalent S(2)O4 tetrahedra. All Co(2)-O(7) bond lengths are 2.03 Å. All Co(2)-O(8) bond lengths are 2.01 Å. In the third Co site, Co(3) is bonded to three equivalent O(3) and three equivalent O(5) atoms to form CoO6 octahedra that share corners with three equivalent S(1)O4 tetrahedra and corners with three equivalent S(2)O4 tetrahedra. All Co(3)-O(3) bond lengths are 2.02 Å. All Co(3)-O(5) bond lengths are 1.98 Å. There are two inequivalent S sites. In the first S site, S(1) is bonded to one O(2), one O(3), one O(4), and one O(8) atom to form SO4 tetrahedra that share  a cornercorner with one Co(1)O6 octahedra,  a cornercorner with one Co(2)O6 octahedra, and  a cornercorner with one Co(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 28-39°. The S(1)-O(2) bond length is 1.50 Å. The S(1)-O(3) bond length is 1.49 Å. The S(1)-O(4) bond length is 1.46 Å. The S(1)-O(8) bond length is 1.49 Å. In the second S site, S(2) is bonded to one O(1), one O(5), one O(6), and one O(7) atom to form SO4 tetrahedra that share  a cornercorner with one Co(1)O6 octahedra,  a cornercorner with one Co(2)O6 octahedra, and  a cornercorner with one Co(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 33-44°. The S(2)-O(1) bond length is 1.46 Å. The S(2)-O(5) bond length is 1.50 Å. The S(2)-O(6) bond length is 1.50 Å. The S(2)-O(7) bond length is 1.49 Å. There are eight inequivalent O sites. In the first O site, O(4) is bonded in a single-bond geometry to one S(1) atom. In the second O site, O(5) is bonded in a bent 150 degrees geometry to one Co(3) and one S(2) atom. In the third O site, O(6) is bonded in a bent 150 degrees geometry to one Co(1) and one S(2) atom. In the fourth O site, O(7) is bonded in a distorted bent 150 degrees geometry to one Co(2) and one S(2) atom. In the fifth O site, O(8) is bonded in a bent 150 degrees geometry to one Co(2) and one S(1) atom. In the sixth O site, O(1) is bonded in a single-bond geometry to one S(2) atom. In the seventh O site, O(2) is bonded in a bent 150 degrees geometry to one Co(1) and one S(1) atom. In the eighth O site, O(3) is bonded in a bent 150 degrees geometry to one Co(3) and one S(1) atom.