MgCo(NiO2)4 crystallizes in the triclinic P-1 space group. Mg(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form MgO6 octahedra that share corners with six equivalent Ni(4)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, and edges with two equivalent Ni(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 10-14°. Co(1) 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 Mg(1)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, edges with two equivalent Ni(3)O6 octahedra, and edges with two equivalent Ni(4)O6 octahedra. There are four inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form NiO6 octahedra that share edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, edges with two equivalent Ni(3)O6 octahedra, and edges with two equivalent Ni(4)O6 octahedra. In the second Ni site, Ni(2) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form NiO6 octahedra that share corners with six equivalent Ni(3)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, and edges with two equivalent Ni(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 10-14°. In the third Ni site, Ni(3) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form NiO6 octahedra that share corners with six equivalent Ni(2)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, and edges with two equivalent Ni(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 10-14°. In the fourth Ni site, Ni(4) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form NiO6 octahedra that share corners with six equivalent Mg(1)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, and edges with two equivalent Ni(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 10-14°. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), one Co(1), one Ni(2), one Ni(3), and one Ni(4) atom to form OMgCoNi3 square pyramids that share corners with five equivalent O(1)MgCoNi3 square pyramids and edges with four equivalent O(3)MgNi4 square pyramids. In the second O site, O(2) is bonded in a see-saw-like geometry to one Mg(1), one Co(1), one Ni(1), and one Ni(4) atom. In the third O site, O(3) is bonded to one Mg(1), one Ni(1), one Ni(2), one Ni(3), and one Ni(4) atom to form OMgNi4 square pyramids that share corners with five equivalent O(3)MgNi4 square pyramids and edges with four equivalent O(1)MgCoNi3 square pyramids. In the fourth O site, O(4) is bonded in a see-saw-like geometry to one Co(1), one Ni(1), one Ni(2), and one Ni(3) atom.
MgCo(NiO2)4 crystallizes in the triclinic P-1 space group. Mg(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form MgO6 octahedra that share corners with six equivalent Ni(4)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, and edges with two equivalent Ni(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 10-14°. Both Mg(1)-O(1) bond lengths are 2.08 Å. Both Mg(1)-O(2) bond lengths are 2.11 Å. Both Mg(1)-O(3) bond lengths are 2.08 Å. Co(1) 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 Mg(1)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, edges with two equivalent Ni(3)O6 octahedra, and edges with two equivalent Ni(4)O6 octahedra. Both Co(1)-O(1) bond lengths are 1.91 Å. Both Co(1)-O(2) bond lengths are 1.90 Å. Both Co(1)-O(4) bond lengths are 1.89 Å. There are four inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form NiO6 octahedra that share edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, edges with two equivalent Ni(3)O6 octahedra, and edges with two equivalent Ni(4)O6 octahedra. Both Ni(1)-O(2) bond lengths are 1.90 Å. Both Ni(1)-O(3) bond lengths are 1.88 Å. Both Ni(1)-O(4) bond lengths are 1.90 Å. In the second Ni site, Ni(2) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form NiO6 octahedra that share corners with six equivalent Ni(3)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, and edges with two equivalent Ni(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 10-14°. Both Ni(2)-O(1) bond lengths are 2.09 Å. Both Ni(2)-O(3) bond lengths are 2.09 Å. Both Ni(2)-O(4) bond lengths are 2.10 Å. In the third Ni site, Ni(3) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form NiO6 octahedra that share corners with six equivalent Ni(2)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, and edges with two equivalent Ni(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 10-14°. Both Ni(3)-O(1) bond lengths are 2.08 Å. Both Ni(3)-O(3) bond lengths are 2.08 Å. Both Ni(3)-O(4) bond lengths are 2.11 Å. In the fourth Ni site, Ni(4) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form NiO6 octahedra that share corners with six equivalent Mg(1)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, and edges with two equivalent Ni(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 10-14°. Both Ni(4)-O(1) bond lengths are 2.08 Å. Both Ni(4)-O(2) bond lengths are 2.09 Å. Both Ni(4)-O(3) bond lengths are 2.09 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), one Co(1), one Ni(2), one Ni(3), and one Ni(4) atom to form OMgCoNi3 square pyramids that share corners with five equivalent O(1)MgCoNi3 square pyramids and edges with four equivalent O(3)MgNi4 square pyramids. In the second O site, O(2) is bonded in a see-saw-like geometry to one Mg(1), one Co(1), one Ni(1), and one Ni(4) atom. In the third O site, O(3) is bonded to one Mg(1), one Ni(1), one Ni(2), one Ni(3), and one Ni(4) atom to form OMgNi4 square pyramids that share corners with five equivalent O(3)MgNi4 square pyramids and edges with four equivalent O(1)MgCoNi3 square pyramids. In the fourth O site, O(4) is bonded in a see-saw-like geometry to one Co(1), one Ni(1), one Ni(2), and one Ni(3) atom.