MgCo2(NiO2)4 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(1), one O(2), one O(3), one O(6), one O(7), and one O(8) atom to form MgO6 octahedra that share corners with six equivalent Ni(2)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, edges with two equivalent Ni(3)O6 octahedra, and edges with two equivalent Ni(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-2°. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded in a distorted rectangular see-saw-like geometry to one O(1), one O(2), one O(5), and one O(6) atom. In the second Co site, Co(2) is bonded in a distorted rectangular see-saw-like geometry to one O(3), one O(4), one O(7), and one O(8) atom. There are four inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(1), one O(2), one O(4), one O(5), one O(7), and one O(8) atom to form NiO6 octahedra that share edges with two equivalent Mg(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 one O(1), one O(2), one O(3), one O(6), one O(7), and one O(8) atom to form NiO6 octahedra that share corners with six equivalent Mg(1)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, edges with two equivalent Ni(3)O6 octahedra, and edges with two equivalent Ni(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-2°. In the third Ni site, Ni(3) is bonded to one O(2), one O(3), one O(4), one O(5), one O(6), and one O(8) atom to form NiO6 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, and edges with two equivalent Ni(4)O6 octahedra. In the fourth Ni site, Ni(4) is bonded to one O(1), one O(3), one O(4), one O(5), one O(6), and one O(7) atom to form NiO6 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, and edges with two equivalent Ni(3)O6 octahedra. There are eight inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), one Co(1), one Ni(1), one Ni(2), and one Ni(4) atom to form a mixture of edge and corner-sharing OMgCoNi3 square pyramids. In the second O site, O(2) is bonded to one Mg(1), one Co(1), one Ni(1), one Ni(2), and one Ni(3) atom to form a mixture of edge and corner-sharing OMgCoNi3 square pyramids. In the third O site, O(3) is bonded to one Mg(1), one Co(2), one Ni(2), one Ni(3), and one Ni(4) atom to form a mixture of edge and corner-sharing OMgCoNi3 square pyramids. In the fourth O site, O(4) is bonded in a rectangular see-saw-like geometry to one Co(2), one Ni(1), one Ni(3), and one Ni(4) atom. In the fifth O site, O(5) is bonded in a distorted rectangular see-saw-like geometry to one Co(1), one Ni(1), one Ni(3), and one Ni(4) atom. In the sixth O site, O(6) is bonded to one Mg(1), one Co(1), one Ni(2), one Ni(3), and one Ni(4) atom to form a mixture of edge and corner-sharing OMgCoNi3 square pyramids. In the seventh O site, O(7) is bonded to one Mg(1), one Co(2), one Ni(1), one Ni(2), and one Ni(4) atom to form a mixture of edge and corner-sharing OMgCoNi3 square pyramids. In the eighth O site, O(8) is bonded to one Mg(1), one Co(2), one Ni(1), one Ni(2), and one Ni(3) atom to form a mixture of edge and corner-sharing OMgCoNi3 square pyramids.
MgCo2(NiO2)4 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(1), one O(2), one O(3), one O(6), one O(7), and one O(8) atom to form MgO6 octahedra that share corners with six equivalent Ni(2)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, edges with two equivalent Ni(3)O6 octahedra, and edges with two equivalent Ni(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-2°. The Mg(1)-O(1) bond length is 2.17 Å. The Mg(1)-O(2) bond length is 2.04 Å. The Mg(1)-O(3) bond length is 2.10 Å. The Mg(1)-O(6) bond length is 2.08 Å. The Mg(1)-O(7) bond length is 2.03 Å. The Mg(1)-O(8) bond length is 2.15 Å. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded in a distorted rectangular see-saw-like geometry to one O(1), one O(2), one O(5), and one O(6) atom. The Co(1)-O(1) bond length is 1.86 Å. The Co(1)-O(2) bond length is 2.08 Å. The Co(1)-O(5) bond length is 1.77 Å. The Co(1)-O(6) bond length is 2.03 Å. In the second Co site, Co(2) is bonded in a distorted rectangular see-saw-like geometry to one O(3), one O(4), one O(7), and one O(8) atom. The Co(2)-O(3) bond length is 2.00 Å. The Co(2)-O(4) bond length is 1.77 Å. The Co(2)-O(7) bond length is 2.10 Å. The Co(2)-O(8) bond length is 1.88 Å. There are four inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(1), one O(2), one O(4), one O(5), one O(7), and one O(8) atom to form NiO6 octahedra that share edges with two equivalent Mg(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. The Ni(1)-O(1) bond length is 2.13 Å. The Ni(1)-O(2) bond length is 2.15 Å. The Ni(1)-O(4) bond length is 1.96 Å. The Ni(1)-O(5) bond length is 1.96 Å. The Ni(1)-O(7) bond length is 2.14 Å. The Ni(1)-O(8) bond length is 2.13 Å. In the second Ni site, Ni(2) is bonded to one O(1), one O(2), one O(3), one O(6), one O(7), and one O(8) atom to form NiO6 octahedra that share corners with six equivalent Mg(1)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, edges with two equivalent Ni(3)O6 octahedra, and edges with two equivalent Ni(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-2°. The Ni(2)-O(1) bond length is 2.22 Å. The Ni(2)-O(2) bond length is 2.10 Å. The Ni(2)-O(3) bond length is 2.16 Å. The Ni(2)-O(6) bond length is 2.14 Å. The Ni(2)-O(7) bond length is 2.09 Å. The Ni(2)-O(8) bond length is 2.21 Å. In the third Ni site, Ni(3) is bonded to one O(2), one O(3), one O(4), one O(5), one O(6), and one O(8) atom to form NiO6 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, and edges with two equivalent Ni(4)O6 octahedra. The Ni(3)-O(2) bond length is 2.13 Å. The Ni(3)-O(3) bond length is 2.14 Å. The Ni(3)-O(4) bond length is 1.96 Å. The Ni(3)-O(5) bond length is 1.98 Å. The Ni(3)-O(6) bond length is 2.12 Å. The Ni(3)-O(8) bond length is 2.15 Å. In the fourth Ni site, Ni(4) is bonded to one O(1), one O(3), one O(4), one O(5), one O(6), and one O(7) atom to form NiO6 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, and edges with two equivalent Ni(3)O6 octahedra. The Ni(4)-O(1) bond length is 2.14 Å. The Ni(4)-O(3) bond length is 2.12 Å. The Ni(4)-O(4) bond length is 1.98 Å. The Ni(4)-O(5) bond length is 1.96 Å. The Ni(4)-O(6) bond length is 2.15 Å. The Ni(4)-O(7) bond length is 2.13 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), one Co(1), one Ni(1), one Ni(2), and one Ni(4) atom to form a mixture of edge and corner-sharing OMgCoNi3 square pyramids. In the second O site, O(2) is bonded to one Mg(1), one Co(1), one Ni(1), one Ni(2), and one Ni(3) atom to form a mixture of edge and corner-sharing OMgCoNi3 square pyramids. In the third O site, O(3) is bonded to one Mg(1), one Co(2), one Ni(2), one Ni(3), and one Ni(4) atom to form a mixture of edge and corner-sharing OMgCoNi3 square pyramids. In the fourth O site, O(4) is bonded in a rectangular see-saw-like geometry to one Co(2), one Ni(1), one Ni(3), and one Ni(4) atom. In the fifth O site, O(5) is bonded in a distorted rectangular see-saw-like geometry to one Co(1), one Ni(1), one Ni(3), and one Ni(4) atom. In the sixth O site, O(6) is bonded to one Mg(1), one Co(1), one Ni(2), one Ni(3), and one Ni(4) atom to form a mixture of edge and corner-sharing OMgCoNi3 square pyramids. In the seventh O site, O(7) is bonded to one Mg(1), one Co(2), one Ni(1), one Ni(2), and one Ni(4) atom to form a mixture of edge and corner-sharing OMgCoNi3 square pyramids. In the eighth O site, O(8) is bonded to one Mg(1), one Co(2), one Ni(1), one Ni(2), and one Ni(3) atom to form a mixture of edge and corner-sharing OMgCoNi3 square pyramids.