MgCd2(NiO2)4 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(1), one O(2), one O(4), one O(5), one O(6), and one O(8) atom to form MgO6 octahedra that share corners with five equivalent Ni(2)O5 trigonal bipyramids, 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. There are four inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(1), one O(2), one O(3), 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(3)O6 octahedra, edges with two equivalent Ni(4)O6 octahedra, and edges with two equivalent Ni(2)O5 trigonal bipyramids. In the second Ni site, Ni(2) is bonded to one O(1), one O(2), one O(5), one O(6), and one O(8) atom to form NiO5 trigonal bipyramids that share  a cornercorner with one Ni(3)O6 octahedra,  a cornercorner with one Ni(4)O6 octahedra, corners with five equivalent Mg(1)O6 octahedra,  an edgeedge with one Ni(3)O6 octahedra,  an edgeedge with one Ni(4)O6 octahedra, and edges with two equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 6-76°. In the third Ni site, Ni(3) is bonded to one O(2), one O(3), one O(4), one O(6), one O(7), and one O(8) atom to form distorted NiO6 octahedra that share  a cornercorner with one Ni(2)O5 trigonal bipyramid, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, edges with two equivalent Ni(4)O6 octahedra, and  an edgeedge with one Ni(2)O5 trigonal bipyramid. In the fourth Ni site, Ni(4) is bonded to one O(1), one O(3), one O(4), one O(5), one O(7), and one O(8) atom to form distorted NiO6 octahedra that share  a cornercorner with one Ni(2)O5 trigonal bipyramid, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, edges with two equivalent Ni(3)O6 octahedra, and  an edgeedge with one Ni(2)O5 trigonal bipyramid. There are two inequivalent Cd sites. In the first Cd site, Cd(1) is bonded in a 4-coordinate geometry to one O(1), one O(3), one O(4), and one O(6) atom. In the second Cd site, Cd(2) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(5), one O(6), and one O(7) atom. There are eight inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), one Ni(1), one Ni(2), one Ni(4), one Cd(1), and one Cd(2) atom to form distorted OMgCd2Ni3 octahedra that share  a cornercorner with one O(3)CdNi3 tetrahedra, corners with five equivalent O(5)MgCdNi3 trigonal bipyramids,  a cornercorner with one O(7)CdNi3 trigonal pyramid,  a cornercorner with one O(4)MgCdNi2 trigonal pyramid,  an edgeedge with one O(6)MgCd2Ni3 octahedra,  an edgeedge with one O(3)CdNi3 tetrahedra, edges with two equivalent O(2)MgCdNi3 trigonal bipyramids,  an edgeedge with one O(7)CdNi3 trigonal pyramid,  an edgeedge with one O(4)MgCdNi2 trigonal pyramid, and  a faceface with one O(6)MgCd2Ni3 octahedra. In the second O site, O(2) is bonded to one Mg(1), one Ni(1), one Ni(2), one Ni(3), and one Cd(2) atom to form OMgCdNi3 trigonal bipyramids that share corners with five equivalent O(6)MgCd2Ni3 octahedra, corners with two equivalent O(3)CdNi3 tetrahedra,  a cornercorner with one O(7)CdNi3 trigonal pyramid, edges with two equivalent O(1)MgCd2Ni3 octahedra, edges with two equivalent O(5)MgCdNi3 trigonal bipyramids,  an edgeedge with one O(7)CdNi3 trigonal pyramid, and  an edgeedge with one O(4)MgCdNi2 trigonal pyramid. The corner-sharing octahedral tilt angles range from 3-40°. In the third O site, O(3) is bonded to one Ni(1), one Ni(3), one Ni(4), and one Cd(1) atom to form OCdNi3 tetrahedra that share  a cornercorner with one O(1)MgCd2Ni3 octahedra,  a cornercorner with one O(6)MgCd2Ni3 octahedra, corners with two equivalent O(2)MgCdNi3 trigonal bipyramids, corners with two equivalent O(5)MgCdNi3 trigonal bipyramids,  a cornercorner with one O(4)MgCdNi2 trigonal pyramid, corners with three equivalent O(7)CdNi3 trigonal pyramids,  an edgeedge with one O(1)MgCd2Ni3 octahedra,  an edgeedge with one O(6)MgCd2Ni3 octahedra, and  an edgeedge with one O(4)MgCdNi2 trigonal pyramid. The corner-sharing octahedral tilt angles range from 63-66°. In the fourth O site, O(4) is bonded to one Mg(1), one Ni(3), one Ni(4), and one Cd(1) atom to form OMgCdNi2 trigonal pyramids that share  a cornercorner with one O(1)MgCd2Ni3 octahedra,  a cornercorner with one O(6)MgCd2Ni3 octahedra,  a cornercorner with one O(3)CdNi3 tetrahedra, corners with two equivalent O(7)CdNi3 trigonal pyramids,  an edgeedge with one O(1)MgCd2Ni3 octahedra,  an edgeedge with one O(6)MgCd2Ni3 octahedra,  an edgeedge with one O(3)CdNi3 tetrahedra,  an edgeedge with one O(2)MgCdNi3 trigonal bipyramid, and  an edgeedge with one O(5)MgCdNi3 trigonal bipyramid. The corner-sharing octahedral tilt angles are 89°. In the fifth O site, O(5) is bonded to one Mg(1), one Ni(1), one Ni(2), one Ni(4), and one Cd(2) atom to form OMgCdNi3 trigonal bipyramids that share corners with five equivalent O(1)MgCd2Ni3 octahedra, corners with two equivalent O(3)CdNi3 tetrahedra,  a cornercorner with one O(7)CdNi3 trigonal pyramid, edges with two equivalent O(6)MgCd2Ni3 octahedra, edges with two equivalent O(2)MgCdNi3 trigonal bipyramids,  an edgeedge with one O(7)CdNi3 trigonal pyramid, and  an edgeedge with one O(4)MgCdNi2 trigonal pyramid. The corner-sharing octahedral tilt angles range from 3-40°. In the sixth O site, O(6) is bonded to one Mg(1), one Ni(1), one Ni(2), one Ni(3), one Cd(1), and one Cd(2) atom to form distorted OMgCd2Ni3 octahedra that share  a cornercorner with one O(3)CdNi3 tetrahedra, corners with five equivalent O(2)MgCdNi3 trigonal bipyramids,  a cornercorner with one O(7)CdNi3 trigonal pyramid,  a cornercorner with one O(4)MgCdNi2 trigonal pyramid,  an edgeedge with one O(1)MgCd2Ni3 octahedra,  an edgeedge with one O(3)CdNi3 tetrahedra, edges with two equivalent O(5)MgCdNi3 trigonal bipyramids,  an edgeedge with one O(7)CdNi3 trigonal pyramid,  an edgeedge with one O(4)MgCdNi2 trigonal pyramid, and  a faceface with one O(1)MgCd2Ni3 octahedra. In the seventh O site, O(7) is bonded to one Ni(1), one Ni(3), one Ni(4), and one Cd(2) atom to form distorted OCdNi3 trigonal pyramids that share  a cornercorner with one O(1)MgCd2Ni3 octahedra,  a cornercorner with one O(6)MgCd2Ni3 octahedra, corners with three equivalent O(3)CdNi3 tetrahedra,  a cornercorner with one O(2)MgCdNi3 trigonal bipyramid,  a cornercorner with one O(5)MgCdNi3 trigonal bipyramid, corners with two equivalent O(4)MgCdNi2 trigonal pyramids,  an edgeedge with one O(1)MgCd2Ni3 octahedra,  an edgeedge with one O(6)MgCd2Ni3 octahedra,  an edgeedge with one O(2)MgCdNi3 trigonal bipyramid, and  an edgeedge with one O(5)MgCdNi3 trigonal bipyramid. The corner-sharing octahedral tilt angles are 85°. In the eighth O site, O(8) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Ni(2), one Ni(3), and one Ni(4) atom.
MgCd2(NiO2)4 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(1), one O(2), one O(4), one O(5), one O(6), and one O(8) atom to form MgO6 octahedra that share corners with five equivalent Ni(2)O5 trigonal bipyramids, 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 Mg(1)-O(1) bond length is 2.22 Å. The Mg(1)-O(2) bond length is 2.13 Å. The Mg(1)-O(4) bond length is 2.18 Å. The Mg(1)-O(5) bond length is 2.14 Å. The Mg(1)-O(6) bond length is 2.22 Å. The Mg(1)-O(8) bond length is 2.11 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(3), 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(3)O6 octahedra, edges with two equivalent Ni(4)O6 octahedra, and edges with two equivalent Ni(2)O5 trigonal bipyramids. The Ni(1)-O(1) bond length is 2.11 Å. The Ni(1)-O(2) bond length is 2.11 Å. The Ni(1)-O(3) bond length is 2.00 Å. The Ni(1)-O(5) bond length is 2.12 Å. The Ni(1)-O(6) bond length is 2.10 Å. The Ni(1)-O(7) bond length is 1.98 Å. In the second Ni site, Ni(2) is bonded to one O(1), one O(2), one O(5), one O(6), and one O(8) atom to form NiO5 trigonal bipyramids that share  a cornercorner with one Ni(3)O6 octahedra,  a cornercorner with one Ni(4)O6 octahedra, corners with five equivalent Mg(1)O6 octahedra,  an edgeedge with one Ni(3)O6 octahedra,  an edgeedge with one Ni(4)O6 octahedra, and edges with two equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 6-76°. The Ni(2)-O(1) bond length is 2.13 Å. The Ni(2)-O(2) bond length is 2.13 Å. The Ni(2)-O(5) bond length is 2.14 Å. The Ni(2)-O(6) bond length is 2.12 Å. The Ni(2)-O(8) bond length is 2.17 Å. In the third Ni site, Ni(3) is bonded to one O(2), one O(3), one O(4), one O(6), one O(7), and one O(8) atom to form distorted NiO6 octahedra that share  a cornercorner with one Ni(2)O5 trigonal bipyramid, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, edges with two equivalent Ni(4)O6 octahedra, and  an edgeedge with one Ni(2)O5 trigonal bipyramid. The Ni(3)-O(2) bond length is 2.13 Å. The Ni(3)-O(3) bond length is 1.90 Å. The Ni(3)-O(4) bond length is 1.91 Å. The Ni(3)-O(6) bond length is 2.43 Å. The Ni(3)-O(7) bond length is 1.91 Å. The Ni(3)-O(8) bond length is 1.94 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(7), and one O(8) atom to form distorted NiO6 octahedra that share  a cornercorner with one Ni(2)O5 trigonal bipyramid, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, edges with two equivalent Ni(3)O6 octahedra, and  an edgeedge with one Ni(2)O5 trigonal bipyramid. The Ni(4)-O(1) bond length is 2.43 Å. The Ni(4)-O(3) bond length is 1.90 Å. The Ni(4)-O(4) bond length is 1.90 Å. The Ni(4)-O(5) bond length is 2.12 Å. The Ni(4)-O(7) bond length is 1.91 Å. The Ni(4)-O(8) bond length is 1.93 Å. There are two inequivalent Cd sites. In the first Cd site, Cd(1) is bonded in a 4-coordinate geometry to one O(1), one O(3), one O(4), and one O(6) atom. The Cd(1)-O(1) bond length is 2.42 Å. The Cd(1)-O(3) bond length is 2.06 Å. The Cd(1)-O(4) bond length is 2.09 Å. The Cd(1)-O(6) bond length is 2.37 Å. In the second Cd site, Cd(2) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(5), one O(6), and one O(7) atom. The Cd(2)-O(1) bond length is 2.39 Å. The Cd(2)-O(2) bond length is 2.22 Å. The Cd(2)-O(5) bond length is 2.20 Å. The Cd(2)-O(6) bond length is 2.42 Å. The Cd(2)-O(7) bond length is 2.15 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), one Ni(1), one Ni(2), one Ni(4), one Cd(1), and one Cd(2) atom to form distorted OMgCd2Ni3 octahedra that share  a cornercorner with one O(3)CdNi3 tetrahedra, corners with five equivalent O(5)MgCdNi3 trigonal bipyramids,  a cornercorner with one O(7)CdNi3 trigonal pyramid,  a cornercorner with one O(4)MgCdNi2 trigonal pyramid,  an edgeedge with one O(6)MgCd2Ni3 octahedra,  an edgeedge with one O(3)CdNi3 tetrahedra, edges with two equivalent O(2)MgCdNi3 trigonal bipyramids,  an edgeedge with one O(7)CdNi3 trigonal pyramid,  an edgeedge with one O(4)MgCdNi2 trigonal pyramid, and  a faceface with one O(6)MgCd2Ni3 octahedra. In the second O site, O(2) is bonded to one Mg(1), one Ni(1), one Ni(2), one Ni(3), and one Cd(2) atom to form OMgCdNi3 trigonal bipyramids that share corners with five equivalent O(6)MgCd2Ni3 octahedra, corners with two equivalent O(3)CdNi3 tetrahedra,  a cornercorner with one O(7)CdNi3 trigonal pyramid, edges with two equivalent O(1)MgCd2Ni3 octahedra, edges with two equivalent O(5)MgCdNi3 trigonal bipyramids,  an edgeedge with one O(7)CdNi3 trigonal pyramid, and  an edgeedge with one O(4)MgCdNi2 trigonal pyramid. The corner-sharing octahedral tilt angles range from 3-40°. In the third O site, O(3) is bonded to one Ni(1), one Ni(3), one Ni(4), and one Cd(1) atom to form OCdNi3 tetrahedra that share  a cornercorner with one O(1)MgCd2Ni3 octahedra,  a cornercorner with one O(6)MgCd2Ni3 octahedra, corners with two equivalent O(2)MgCdNi3 trigonal bipyramids, corners with two equivalent O(5)MgCdNi3 trigonal bipyramids,  a cornercorner with one O(4)MgCdNi2 trigonal pyramid, corners with three equivalent O(7)CdNi3 trigonal pyramids,  an edgeedge with one O(1)MgCd2Ni3 octahedra,  an edgeedge with one O(6)MgCd2Ni3 octahedra, and  an edgeedge with one O(4)MgCdNi2 trigonal pyramid. The corner-sharing octahedral tilt angles range from 63-66°. In the fourth O site, O(4) is bonded to one Mg(1), one Ni(3), one Ni(4), and one Cd(1) atom to form OMgCdNi2 trigonal pyramids that share  a cornercorner with one O(1)MgCd2Ni3 octahedra,  a cornercorner with one O(6)MgCd2Ni3 octahedra,  a cornercorner with one O(3)CdNi3 tetrahedra, corners with two equivalent O(7)CdNi3 trigonal pyramids,  an edgeedge with one O(1)MgCd2Ni3 octahedra,  an edgeedge with one O(6)MgCd2Ni3 octahedra,  an edgeedge with one O(3)CdNi3 tetrahedra,  an edgeedge with one O(2)MgCdNi3 trigonal bipyramid, and  an edgeedge with one O(5)MgCdNi3 trigonal bipyramid. The corner-sharing octahedral tilt angles are 89°. In the fifth O site, O(5) is bonded to one Mg(1), one Ni(1), one Ni(2), one Ni(4), and one Cd(2) atom to form OMgCdNi3 trigonal bipyramids that share corners with five equivalent O(1)MgCd2Ni3 octahedra, corners with two equivalent O(3)CdNi3 tetrahedra,  a cornercorner with one O(7)CdNi3 trigonal pyramid, edges with two equivalent O(6)MgCd2Ni3 octahedra, edges with two equivalent O(2)MgCdNi3 trigonal bipyramids,  an edgeedge with one O(7)CdNi3 trigonal pyramid, and  an edgeedge with one O(4)MgCdNi2 trigonal pyramid. The corner-sharing octahedral tilt angles range from 3-40°. In the sixth O site, O(6) is bonded to one Mg(1), one Ni(1), one Ni(2), one Ni(3), one Cd(1), and one Cd(2) atom to form distorted OMgCd2Ni3 octahedra that share  a cornercorner with one O(3)CdNi3 tetrahedra, corners with five equivalent O(2)MgCdNi3 trigonal bipyramids,  a cornercorner with one O(7)CdNi3 trigonal pyramid,  a cornercorner with one O(4)MgCdNi2 trigonal pyramid,  an edgeedge with one O(1)MgCd2Ni3 octahedra,  an edgeedge with one O(3)CdNi3 tetrahedra, edges with two equivalent O(5)MgCdNi3 trigonal bipyramids,  an edgeedge with one O(7)CdNi3 trigonal pyramid,  an edgeedge with one O(4)MgCdNi2 trigonal pyramid, and  a faceface with one O(1)MgCd2Ni3 octahedra. In the seventh O site, O(7) is bonded to one Ni(1), one Ni(3), one Ni(4), and one Cd(2) atom to form distorted OCdNi3 trigonal pyramids that share  a cornercorner with one O(1)MgCd2Ni3 octahedra,  a cornercorner with one O(6)MgCd2Ni3 octahedra, corners with three equivalent O(3)CdNi3 tetrahedra,  a cornercorner with one O(2)MgCdNi3 trigonal bipyramid,  a cornercorner with one O(5)MgCdNi3 trigonal bipyramid, corners with two equivalent O(4)MgCdNi2 trigonal pyramids,  an edgeedge with one O(1)MgCd2Ni3 octahedra,  an edgeedge with one O(6)MgCd2Ni3 octahedra,  an edgeedge with one O(2)MgCdNi3 trigonal bipyramid, and  an edgeedge with one O(5)MgCdNi3 trigonal bipyramid. The corner-sharing octahedral tilt angles are 85°. In the eighth O site, O(8) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Ni(2), one Ni(3), and one Ni(4) atom.