MgZn2(NiO2)4 crystallizes in the monoclinic C2/m space group. Mg(1) is bonded to two equivalent O(3) and four equivalent O(2) atoms to form MgO6 octahedra that share corners with six equivalent Ni(2)O6 octahedra, edges with two equivalent Ni(3)O6 octahedra, and edges with four equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 3-4°. There are three inequivalent Ni sites. In the first Ni site, 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 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. In the second Ni site, Ni(2) is bonded to two equivalent O(3) and four equivalent O(2) atoms to form NiO6 octahedra that share corners with six equivalent Mg(1)O6 octahedra, edges with two equivalent Ni(3)O6 octahedra, and edges with four equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 3-4°. In the third Ni site, Ni(3) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form NiO6 octahedra that share edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, and edges with four equivalent Ni(1)O6 octahedra. Zn(1) is bonded in a rectangular see-saw-like geometry to one O(1), one O(3), and two equivalent O(2) atoms. There are three inequivalent O sites. In the first O site, O(1) is bonded to one Ni(3), two equivalent Ni(1), and one Zn(1) atom to form OZnNi3 tetrahedra that share corners with three equivalent O(3)MgZnNi3 square pyramids, corners with six equivalent O(2)MgZnNi3 square pyramids, corners with three equivalent O(1)ZnNi3 tetrahedra,  an edgeedge with one O(3)MgZnNi3 square pyramid, and edges with two equivalent O(2)MgZnNi3 square pyramids. In the second O site, O(2) is bonded to one Mg(1), one Ni(1), one Ni(2), one Ni(3), and one Zn(1) atom to form OMgZnNi3 square pyramids that share  a cornercorner with one O(3)MgZnNi3 square pyramid, corners with five equivalent O(2)MgZnNi3 square pyramids, corners with three equivalent O(1)ZnNi3 tetrahedra, edges with three equivalent O(2)MgZnNi3 square pyramids, edges with three equivalent O(3)MgZnNi3 square pyramids, and  an edgeedge with one O(1)ZnNi3 tetrahedra. In the third O site, O(3) is bonded to one Mg(1), one Ni(2), two equivalent Ni(1), and one Zn(1) atom to form OMgZnNi3 square pyramids that share corners with two equivalent O(2)MgZnNi3 square pyramids, corners with four equivalent O(3)MgZnNi3 square pyramids, corners with three equivalent O(1)ZnNi3 tetrahedra, edges with six equivalent O(2)MgZnNi3 square pyramids, and  an edgeedge with one O(1)ZnNi3 tetrahedra.
MgZn2(NiO2)4 crystallizes in the monoclinic C2/m space group. Mg(1) is bonded to two equivalent O(3) and four equivalent O(2) atoms to form MgO6 octahedra that share corners with six equivalent Ni(2)O6 octahedra, edges with two equivalent Ni(3)O6 octahedra, and edges with four equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 3-4°. Both Mg(1)-O(3) bond lengths are 2.13 Å. All Mg(1)-O(2) bond lengths are 2.10 Å. There are three inequivalent Ni sites. In the first Ni site, 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 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. Both Ni(1)-O(1) bond lengths are 1.92 Å. Both Ni(1)-O(2) bond lengths are 2.12 Å. Both Ni(1)-O(3) bond lengths are 2.06 Å. In the second Ni site, Ni(2) is bonded to two equivalent O(3) and four equivalent O(2) atoms to form NiO6 octahedra that share corners with six equivalent Mg(1)O6 octahedra, edges with two equivalent Ni(3)O6 octahedra, and edges with four equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 3-4°. Both Ni(2)-O(3) bond lengths are 2.19 Å. All Ni(2)-O(2) bond lengths are 2.14 Å. In the third Ni site, Ni(3) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form NiO6 octahedra that share edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, and edges with four equivalent Ni(1)O6 octahedra. Both Ni(3)-O(1) bond lengths are 1.92 Å. All Ni(3)-O(2) bond lengths are 2.08 Å. Zn(1) is bonded in a rectangular see-saw-like geometry to one O(1), one O(3), and two equivalent O(2) atoms. The Zn(1)-O(1) bond length is 1.87 Å. The Zn(1)-O(3) bond length is 2.08 Å. Both Zn(1)-O(2) bond lengths are 2.06 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded to one Ni(3), two equivalent Ni(1), and one Zn(1) atom to form OZnNi3 tetrahedra that share corners with three equivalent O(3)MgZnNi3 square pyramids, corners with six equivalent O(2)MgZnNi3 square pyramids, corners with three equivalent O(1)ZnNi3 tetrahedra,  an edgeedge with one O(3)MgZnNi3 square pyramid, and edges with two equivalent O(2)MgZnNi3 square pyramids. In the second O site, O(2) is bonded to one Mg(1), one Ni(1), one Ni(2), one Ni(3), and one Zn(1) atom to form OMgZnNi3 square pyramids that share  a cornercorner with one O(3)MgZnNi3 square pyramid, corners with five equivalent O(2)MgZnNi3 square pyramids, corners with three equivalent O(1)ZnNi3 tetrahedra, edges with three equivalent O(2)MgZnNi3 square pyramids, edges with three equivalent O(3)MgZnNi3 square pyramids, and  an edgeedge with one O(1)ZnNi3 tetrahedra. In the third O site, O(3) is bonded to one Mg(1), one Ni(2), two equivalent Ni(1), and one Zn(1) atom to form OMgZnNi3 square pyramids that share corners with two equivalent O(2)MgZnNi3 square pyramids, corners with four equivalent O(3)MgZnNi3 square pyramids, corners with three equivalent O(1)ZnNi3 tetrahedra, edges with six equivalent O(2)MgZnNi3 square pyramids, and  an edgeedge with one O(1)ZnNi3 tetrahedra.