TlNiO3 crystallizes in the monoclinic Pm space group. Ni(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form distorted corner-sharing NiO6 pentagonal pyramids. Tl(1) is bonded in a 5-coordinate geometry to one O(1), two equivalent O(2), and two equivalent O(3) atoms. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted T-shaped geometry to two equivalent Ni(1) and one Tl(1) atom. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Ni(1) and two equivalent Tl(1) atoms. In the third O site, O(3) is bonded in a distorted see-saw-like geometry to two equivalent Ni(1) and two equivalent Tl(1) atoms.
TlNiO3 crystallizes in the monoclinic Pm space group. Ni(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form distorted corner-sharing NiO6 pentagonal pyramids. Both Ni(1)-O(1) bond lengths are 1.92 Å. There is one shorter (1.99 Å) and one longer (2.01 Å) Ni(1)-O(2) bond length. There is one shorter (2.00 Å) and one longer (2.02 Å) Ni(1)-O(3) bond length. Tl(1) is bonded in a 5-coordinate geometry to one O(1), two equivalent O(2), and two equivalent O(3) atoms. The Tl(1)-O(1) bond length is 2.31 Å. Both Tl(1)-O(2) bond lengths are 2.44 Å. Both Tl(1)-O(3) bond lengths are 2.39 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted T-shaped geometry to two equivalent Ni(1) and one Tl(1) atom. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Ni(1) and two equivalent Tl(1) atoms. In the third O site, O(3) is bonded in a distorted see-saw-like geometry to two equivalent Ni(1) and two equivalent Tl(1) atoms.