MgZn2(NiO2)4 crystallizes in the monoclinic Pm space group. Mg(1) is bonded to two equivalent O(1) and two equivalent O(3) atoms to form MgO4 tetrahedra that share corners with two equivalent Mg(1)O4 tetrahedra, corners with four equivalent Ni(1)O5 trigonal bipyramids, corners with two equivalent Zn(2)O4 trigonal pyramids, and edges with two equivalent Zn(2)O4 trigonal pyramids. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(2), two equivalent O(1), and two equivalent O(5) atoms to form distorted NiO5 trigonal bipyramids that share corners with two equivalent Mg(1)O4 tetrahedra, corners with four equivalent Ni(2)O5 trigonal bipyramids,  a cornercorner with one Zn(1)O4 trigonal pyramid, corners with two equivalent Zn(2)O4 trigonal pyramids,  an edgeedge with one Ni(2)O5 trigonal bipyramid, and edges with two equivalent Ni(1)O5 trigonal bipyramids. In the second Ni site, Ni(2) is bonded to one O(4), two equivalent O(2), and two equivalent O(5) atoms to form NiO5 trigonal bipyramids that share  a cornercorner with one Ni(2)O5 trigonal bipyramid, corners with four equivalent Ni(1)O5 trigonal bipyramids, corners with four equivalent Zn(1)O4 trigonal pyramids,  an edgeedge with one Ni(1)O5 trigonal bipyramid, and edges with two equivalent Ni(2)O5 trigonal bipyramids. There are two inequivalent Zn sites. In the first Zn site, Zn(1) is bonded to two equivalent O(2) and two equivalent O(4) atoms to form distorted ZnO4 trigonal pyramids that share corners with two equivalent Ni(1)O5 trigonal bipyramids, corners with eight equivalent Ni(2)O5 trigonal bipyramids, and corners with two equivalent Zn(1)O4 trigonal pyramids. In the second Zn site, Zn(2) is bonded to two equivalent O(1) and two equivalent O(3) atoms to form distorted ZnO4 trigonal pyramids that share corners with two equivalent Mg(1)O4 tetrahedra, corners with four equivalent Ni(1)O5 trigonal bipyramids, corners with two equivalent Zn(2)O4 trigonal pyramids, and edges with two equivalent Mg(1)O4 tetrahedra. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted see-saw-like geometry to one Mg(1), two equivalent Ni(1), and one Zn(2) atom. In the second O site, O(2) is bonded to one Ni(1), two equivalent Ni(2), and one Zn(1) atom to form distorted OZnNi3 tetrahedra that share corners with three equivalent O(2)ZnNi3 tetrahedra and corners with four equivalent O(4)Zn2Ni2 tetrahedra. In the third O site, O(3) is bonded in a square co-planar geometry to two equivalent Mg(1) and two equivalent Zn(2) atoms. In the fourth O site, O(4) is bonded to two equivalent Ni(2) and two equivalent Zn(1) atoms to form OZn2Ni2 tetrahedra that share corners with two equivalent O(4)Zn2Ni2 tetrahedra and corners with eight equivalent O(2)ZnNi3 tetrahedra. In the fifth O site, O(5) is bonded in a rectangular see-saw-like geometry to two equivalent Ni(1) and two equivalent Ni(2) atoms.
MgZn2(NiO2)4 crystallizes in the monoclinic Pm space group. Mg(1) is bonded to two equivalent O(1) and two equivalent O(3) atoms to form MgO4 tetrahedra that share corners with two equivalent Mg(1)O4 tetrahedra, corners with four equivalent Ni(1)O5 trigonal bipyramids, corners with two equivalent Zn(2)O4 trigonal pyramids, and edges with two equivalent Zn(2)O4 trigonal pyramids. Both Mg(1)-O(1) bond lengths are 1.96 Å. There is one shorter (1.91 Å) and one longer (1.92 Å) Mg(1)-O(3) bond length. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(2), two equivalent O(1), and two equivalent O(5) atoms to form distorted NiO5 trigonal bipyramids that share corners with two equivalent Mg(1)O4 tetrahedra, corners with four equivalent Ni(2)O5 trigonal bipyramids,  a cornercorner with one Zn(1)O4 trigonal pyramid, corners with two equivalent Zn(2)O4 trigonal pyramids,  an edgeedge with one Ni(2)O5 trigonal bipyramid, and edges with two equivalent Ni(1)O5 trigonal bipyramids. The Ni(1)-O(2) bond length is 2.04 Å. There is one shorter (1.98 Å) and one longer (2.00 Å) Ni(1)-O(1) bond length. There is one shorter (1.99 Å) and one longer (2.11 Å) Ni(1)-O(5) bond length. In the second Ni site, Ni(2) is bonded to one O(4), two equivalent O(2), and two equivalent O(5) atoms to form NiO5 trigonal bipyramids that share  a cornercorner with one Ni(2)O5 trigonal bipyramid, corners with four equivalent Ni(1)O5 trigonal bipyramids, corners with four equivalent Zn(1)O4 trigonal pyramids,  an edgeedge with one Ni(1)O5 trigonal bipyramid, and edges with two equivalent Ni(2)O5 trigonal bipyramids. The Ni(2)-O(4) bond length is 2.01 Å. There is one shorter (1.95 Å) and one longer (2.00 Å) Ni(2)-O(2) bond length. There is one shorter (1.94 Å) and one longer (2.12 Å) Ni(2)-O(5) bond length. There are two inequivalent Zn sites. In the first Zn site, Zn(1) is bonded to two equivalent O(2) and two equivalent O(4) atoms to form distorted ZnO4 trigonal pyramids that share corners with two equivalent Ni(1)O5 trigonal bipyramids, corners with eight equivalent Ni(2)O5 trigonal bipyramids, and corners with two equivalent Zn(1)O4 trigonal pyramids. Both Zn(1)-O(2) bond lengths are 2.08 Å. There is one shorter (1.98 Å) and one longer (2.03 Å) Zn(1)-O(4) bond length. In the second Zn site, Zn(2) is bonded to two equivalent O(1) and two equivalent O(3) atoms to form distorted ZnO4 trigonal pyramids that share corners with two equivalent Mg(1)O4 tetrahedra, corners with four equivalent Ni(1)O5 trigonal bipyramids, corners with two equivalent Zn(2)O4 trigonal pyramids, and edges with two equivalent Mg(1)O4 tetrahedra. Both Zn(2)-O(1) bond lengths are 1.99 Å. There is one shorter (1.95 Å) and one longer (2.00 Å) Zn(2)-O(3) bond length. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted see-saw-like geometry to one Mg(1), two equivalent Ni(1), and one Zn(2) atom. In the second O site, O(2) is bonded to one Ni(1), two equivalent Ni(2), and one Zn(1) atom to form distorted OZnNi3 tetrahedra that share corners with three equivalent O(2)ZnNi3 tetrahedra and corners with four equivalent O(4)Zn2Ni2 tetrahedra. In the third O site, O(3) is bonded in a square co-planar geometry to two equivalent Mg(1) and two equivalent Zn(2) atoms. In the fourth O site, O(4) is bonded to two equivalent Ni(2) and two equivalent Zn(1) atoms to form OZn2Ni2 tetrahedra that share corners with two equivalent O(4)Zn2Ni2 tetrahedra and corners with eight equivalent O(2)ZnNi3 tetrahedra. In the fifth O site, O(5) is bonded in a rectangular see-saw-like geometry to two equivalent Ni(1) and two equivalent Ni(2) atoms.