Ni5(SeO3)4Br2 crystallizes in the triclinic P-1 space group. There are three inequivalent Ni sites. In the first Ni site, Ni(1) is bonded in a distorted square co-planar geometry to two equivalent O(3), two equivalent O(6), and two equivalent Br(1) atoms. In the second Ni site, Ni(2) is bonded to one O(1), one O(3), one O(4), and two equivalent O(5) atoms to form distorted NiO5 square pyramids that share  an edgeedge with one Ni(3)BrO5 octahedra and  an edgeedge with one Ni(2)O5 square pyramid. In the third Ni site, Ni(3) is bonded to one O(1), one O(4), one O(6), two equivalent O(2), and one Br(1) atom to form distorted NiBrO5 octahedra that share  an edgeedge with one Ni(3)BrO5 octahedra and  an edgeedge with one Ni(2)O5 square pyramid. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a trigonal non-coplanar geometry to one O(1), one O(5), and one O(6) atom. In the second Se site, Se(2) is bonded in a trigonal non-coplanar geometry to one O(2), one O(3), and one O(4) atom. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Ni(2), one Ni(3), and one Se(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Ni(3) and one Se(2) atom. In the third O site, O(3) is bonded in a trigonal planar geometry to one Ni(1), one Ni(2), and one Se(2) atom. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Ni(2), one Ni(3), and one Se(2) atom. In the fifth O site, O(5) is bonded in a trigonal planar geometry to two equivalent Ni(2) and one Se(1) atom. In the sixth O site, O(6) is bonded in a trigonal planar geometry to one Ni(1), one Ni(3), and one Se(1) atom. Br(1) is bonded in a 2-coordinate geometry to one Ni(1) and one Ni(3) atom.
Ni5(SeO3)4Br2 crystallizes in the triclinic P-1 space group. There are three inequivalent Ni sites. In the first Ni site, Ni(1) is bonded in a distorted square co-planar geometry to two equivalent O(3), two equivalent O(6), and two equivalent Br(1) atoms. Both Ni(1)-O(3) bond lengths are 2.08 Å. Both Ni(1)-O(6) bond lengths are 2.04 Å. Both Ni(1)-Br(1) bond lengths are 2.70 Å. In the second Ni site, Ni(2) is bonded to one O(1), one O(3), one O(4), and two equivalent O(5) atoms to form distorted NiO5 square pyramids that share  an edgeedge with one Ni(3)BrO5 octahedra and  an edgeedge with one Ni(2)O5 square pyramid. The Ni(2)-O(1) bond length is 2.09 Å. The Ni(2)-O(3) bond length is 2.09 Å. The Ni(2)-O(4) bond length is 2.02 Å. There is one shorter (2.05 Å) and one longer (2.06 Å) Ni(2)-O(5) bond length. In the third Ni site, Ni(3) is bonded to one O(1), one O(4), one O(6), two equivalent O(2), and one Br(1) atom to form distorted NiBrO5 octahedra that share  an edgeedge with one Ni(3)BrO5 octahedra and  an edgeedge with one Ni(2)O5 square pyramid. The Ni(3)-O(1) bond length is 2.16 Å. The Ni(3)-O(4) bond length is 2.06 Å. The Ni(3)-O(6) bond length is 2.14 Å. There is one shorter (2.04 Å) and one longer (2.05 Å) Ni(3)-O(2) bond length. The Ni(3)-Br(1) bond length is 2.67 Å. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a trigonal non-coplanar geometry to one O(1), one O(5), and one O(6) atom. The Se(1)-O(1) bond length is 1.74 Å. The Se(1)-O(5) bond length is 1.74 Å. The Se(1)-O(6) bond length is 1.73 Å. In the second Se site, Se(2) is bonded in a trigonal non-coplanar geometry to one O(2), one O(3), and one O(4) atom. The Se(2)-O(2) bond length is 1.72 Å. The Se(2)-O(3) bond length is 1.74 Å. The Se(2)-O(4) bond length is 1.74 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Ni(2), one Ni(3), and one Se(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Ni(3) and one Se(2) atom. In the third O site, O(3) is bonded in a trigonal planar geometry to one Ni(1), one Ni(2), and one Se(2) atom. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Ni(2), one Ni(3), and one Se(2) atom. In the fifth O site, O(5) is bonded in a trigonal planar geometry to two equivalent Ni(2) and one Se(1) atom. In the sixth O site, O(6) is bonded in a trigonal planar geometry to one Ni(1), one Ni(3), and one Se(1) atom. Br(1) is bonded in a 2-coordinate geometry to one Ni(1) and one Ni(3) atom.