Ni(SO4)2 crystallizes in the trigonal R3 space group. There are three inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to three equivalent O(2) and three equivalent O(6) atoms to form NiO6 octahedra that share corners with three equivalent S(1)O4 tetrahedra and corners with three equivalent S(2)O4 tetrahedra. In the second Ni site, Ni(2) is bonded to three equivalent O(7) and three equivalent O(8) atoms to form NiO6 octahedra that share corners with three equivalent S(1)O4 tetrahedra and corners with three equivalent S(2)O4 tetrahedra. In the third Ni site, Ni(3) is bonded to three equivalent O(3) and three equivalent O(5) atoms to form NiO6 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 Ni(1)O6 octahedra,  a cornercorner with one Ni(2)O6 octahedra, and  a cornercorner with one Ni(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 31-44°. 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 Ni(1)O6 octahedra,  a cornercorner with one Ni(2)O6 octahedra, and  a cornercorner with one Ni(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 41-46°. 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 Ni(3) and one S(2) atom. In the third O site, O(6) is bonded in a distorted bent 150 degrees geometry to one Ni(1) and one S(2) atom. In the fourth O site, O(7) is bonded in a distorted bent 120 degrees geometry to one Ni(2) and one S(2) atom. In the fifth O site, O(8) is bonded in a bent 150 degrees geometry to one Ni(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 distorted bent 150 degrees geometry to one Ni(1) and one S(1) atom. In the eighth O site, O(3) is bonded in a distorted bent 150 degrees geometry to one Ni(3) and one S(1) atom.
Ni(SO4)2 crystallizes in the trigonal R3 space group. There are three inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to three equivalent O(2) and three equivalent O(6) atoms to form NiO6 octahedra that share corners with three equivalent S(1)O4 tetrahedra and corners with three equivalent S(2)O4 tetrahedra. All Ni(1)-O(2) bond lengths are 2.05 Å. All Ni(1)-O(6) bond lengths are 2.03 Å. In the second Ni site, Ni(2) is bonded to three equivalent O(7) and three equivalent O(8) atoms to form NiO6 octahedra that share corners with three equivalent S(1)O4 tetrahedra and corners with three equivalent S(2)O4 tetrahedra. All Ni(2)-O(7) bond lengths are 2.07 Å. All Ni(2)-O(8) bond lengths are 2.08 Å. In the third Ni site, Ni(3) is bonded to three equivalent O(3) and three equivalent O(5) atoms to form NiO6 octahedra that share corners with three equivalent S(1)O4 tetrahedra and corners with three equivalent S(2)O4 tetrahedra. All Ni(3)-O(3) bond lengths are 2.02 Å. All Ni(3)-O(5) bond lengths are 2.05 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 Ni(1)O6 octahedra,  a cornercorner with one Ni(2)O6 octahedra, and  a cornercorner with one Ni(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 31-44°. The S(1)-O(2) bond length is 1.48 Å. The S(1)-O(3) bond length is 1.50 Å. The S(1)-O(4) bond length is 1.47 Å. The S(1)-O(8) bond length is 1.48 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 Ni(1)O6 octahedra,  a cornercorner with one Ni(2)O6 octahedra, and  a cornercorner with one Ni(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 41-46°. The S(2)-O(1) bond length is 1.48 Å. The S(2)-O(5) bond length is 1.48 Å. The S(2)-O(6) bond length is 1.49 Å. The S(2)-O(7) bond length is 1.47 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 Ni(3) and one S(2) atom. In the third O site, O(6) is bonded in a distorted bent 150 degrees geometry to one Ni(1) and one S(2) atom. In the fourth O site, O(7) is bonded in a distorted bent 120 degrees geometry to one Ni(2) and one S(2) atom. In the fifth O site, O(8) is bonded in a bent 150 degrees geometry to one Ni(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 distorted bent 150 degrees geometry to one Ni(1) and one S(1) atom. In the eighth O site, O(3) is bonded in a distorted bent 150 degrees geometry to one Ni(3) and one S(1) atom.