Co4NiO8 crystallizes in the triclinic P-1 space group. There are four inequivalent Co sites. In the first Co site, Co(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form CoO6 octahedra that share corners with six equivalent Co(2)O6 octahedra, edges with two equivalent Co(3)O6 octahedra, edges with two equivalent Co(4)O6 octahedra, and edges with two equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 11-13°. In the second Co site, Co(2) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form CoO6 octahedra that share corners with six equivalent Co(1)O6 octahedra, edges with two equivalent Co(3)O6 octahedra, edges with two equivalent Co(4)O6 octahedra, and edges with two equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 11-13°. In the third Co site, Co(3) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form CoO6 octahedra that share edges with two equivalent Co(1)O6 octahedra, edges with two equivalent Co(2)O6 octahedra, edges with two equivalent Co(4)O6 octahedra, and edges with two equivalent Ni(1)O6 octahedra. In the fourth Co site, Co(4) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form CoO6 octahedra that share edges with two equivalent Co(1)O6 octahedra, edges with two equivalent Co(2)O6 octahedra, edges with two equivalent Co(3)O6 octahedra, and edges with two equivalent Ni(1)O6 octahedra. Ni(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form NiO6 octahedra that share edges with two equivalent Co(1)O6 octahedra, edges with two equivalent Co(2)O6 octahedra, edges with two equivalent Co(3)O6 octahedra, and edges with two equivalent Co(4)O6 octahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted T-shaped geometry to one Co(3), one Co(4), and one Ni(1) atom. In the second O site, O(2) is bonded in a rectangular see-saw-like geometry to one Co(1), one Co(2), one Co(4), and one Ni(1) atom. In the third O site, O(3) is bonded in a rectangular see-saw-like geometry to one Co(1), one Co(2), one Co(3), and one Ni(1) atom. In the fourth O site, O(4) is bonded in a rectangular see-saw-like geometry to one Co(1), one Co(2), one Co(3), and one Co(4) atom.
Co4NiO8 crystallizes in the triclinic P-1 space group. There are four inequivalent Co sites. In the first Co site, Co(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form CoO6 octahedra that share corners with six equivalent Co(2)O6 octahedra, edges with two equivalent Co(3)O6 octahedra, edges with two equivalent Co(4)O6 octahedra, and edges with two equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 11-13°. Both Co(1)-O(2) bond lengths are 2.11 Å. Both Co(1)-O(3) bond lengths are 2.20 Å. Both Co(1)-O(4) bond lengths are 2.13 Å. In the second Co site, Co(2) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form CoO6 octahedra that share corners with six equivalent Co(1)O6 octahedra, edges with two equivalent Co(3)O6 octahedra, edges with two equivalent Co(4)O6 octahedra, and edges with two equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 11-13°. Both Co(2)-O(2) bond lengths are 1.95 Å. Both Co(2)-O(3) bond lengths are 1.95 Å. Both Co(2)-O(4) bond lengths are 1.95 Å. In the third Co site, Co(3) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form CoO6 octahedra that share edges with two equivalent Co(1)O6 octahedra, edges with two equivalent Co(2)O6 octahedra, edges with two equivalent Co(4)O6 octahedra, and edges with two equivalent Ni(1)O6 octahedra. Both Co(3)-O(1) bond lengths are 1.87 Å. Both Co(3)-O(3) bond lengths are 1.90 Å. Both Co(3)-O(4) bond lengths are 1.88 Å. In the fourth Co site, Co(4) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form CoO6 octahedra that share edges with two equivalent Co(1)O6 octahedra, edges with two equivalent Co(2)O6 octahedra, edges with two equivalent Co(3)O6 octahedra, and edges with two equivalent Ni(1)O6 octahedra. Both Co(4)-O(1) bond lengths are 1.90 Å. Both Co(4)-O(2) bond lengths are 1.90 Å. Both Co(4)-O(4) bond lengths are 1.91 Å. Ni(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form NiO6 octahedra that share edges with two equivalent Co(1)O6 octahedra, edges with two equivalent Co(2)O6 octahedra, edges with two equivalent Co(3)O6 octahedra, and edges with two equivalent Co(4)O6 octahedra. Both Ni(1)-O(1) bond lengths are 1.88 Å. Both Ni(1)-O(2) bond lengths are 1.88 Å. Both Ni(1)-O(3) bond lengths are 1.88 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted T-shaped geometry to one Co(3), one Co(4), and one Ni(1) atom. In the second O site, O(2) is bonded in a rectangular see-saw-like geometry to one Co(1), one Co(2), one Co(4), and one Ni(1) atom. In the third O site, O(3) is bonded in a rectangular see-saw-like geometry to one Co(1), one Co(2), one Co(3), and one Ni(1) atom. In the fourth O site, O(4) is bonded in a rectangular see-saw-like geometry to one Co(1), one Co(2), one Co(3), and one Co(4) atom.