Mg(NiO2)4 crystallizes in the triclinic P1 space group. Mg(1) is bonded in a body-centered cubic geometry to two equivalent O(5), two equivalent O(6), two equivalent O(7), and two equivalent O(8) atoms. There are four inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(2), one O(7), two equivalent O(4), and two equivalent O(5) atoms to form a mixture of edge and corner-sharing NiO6 octahedra. The corner-sharing octahedral tilt angles are 53°. In the second Ni site, Ni(2) is bonded to one O(4), one O(8), two equivalent O(3), and two equivalent O(6) atoms to form a mixture of edge and corner-sharing NiO6 octahedra. The corner-sharing octahedral tilt angles are 53°. In the third Ni site, Ni(3) is bonded to one O(1), one O(6), two equivalent O(2), and two equivalent O(8) atoms to form a mixture of edge and corner-sharing NiO6 octahedra. The corner-sharing octahedral tilt angles are 53°. In the fourth Ni site, Ni(4) is bonded to one O(3), one O(5), two equivalent O(1), and two equivalent O(7) atoms to form a mixture of edge and corner-sharing NiO6 octahedra. The corner-sharing octahedral tilt angles are 53°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Ni(3) and two equivalent Ni(4) atoms. In the second O site, O(2) is bonded in a trigonal planar geometry to one Ni(1) and two equivalent Ni(3) atoms. In the third O site, O(3) is bonded in a trigonal planar geometry to one Ni(4) and two equivalent Ni(2) atoms. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Ni(2) and two equivalent Ni(1) atoms. In the fifth O site, O(5) is bonded to two equivalent Mg(1), one Ni(4), and two equivalent Ni(1) atoms to form a mixture of distorted edge and corner-sharing OMg2Ni3 trigonal bipyramids. In the sixth O site, O(6) is bonded to two equivalent Mg(1), one Ni(3), and two equivalent Ni(2) atoms to form a mixture of distorted edge and corner-sharing OMg2Ni3 trigonal bipyramids. In the seventh O site, O(7) is bonded to two equivalent Mg(1), one Ni(1), and two equivalent Ni(4) atoms to form a mixture of distorted edge and corner-sharing OMg2Ni3 trigonal bipyramids. In the eighth O site, O(8) is bonded to two equivalent Mg(1), one Ni(2), and two equivalent Ni(3) atoms to form a mixture of distorted edge and corner-sharing OMg2Ni3 trigonal bipyramids.
Mg(NiO2)4 crystallizes in the triclinic P1 space group. Mg(1) is bonded in a body-centered cubic geometry to two equivalent O(5), two equivalent O(6), two equivalent O(7), and two equivalent O(8) atoms. There is one shorter (2.54 Å) and one longer (2.55 Å) Mg(1)-O(5) bond length. There is one shorter (2.55 Å) and one longer (2.57 Å) Mg(1)-O(6) bond length. There is one shorter (2.56 Å) and one longer (2.58 Å) Mg(1)-O(7) bond length. There is one shorter (2.54 Å) and one longer (2.56 Å) Mg(1)-O(8) bond length. There are four inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(2), one O(7), two equivalent O(4), and two equivalent O(5) atoms to form a mixture of edge and corner-sharing NiO6 octahedra. The corner-sharing octahedral tilt angles are 53°. The Ni(1)-O(2) bond length is 1.82 Å. The Ni(1)-O(7) bond length is 1.95 Å. Both Ni(1)-O(4) bond lengths are 1.88 Å. There is one shorter (2.01 Å) and one longer (2.02 Å) Ni(1)-O(5) bond length. In the second Ni site, Ni(2) is bonded to one O(4), one O(8), two equivalent O(3), and two equivalent O(6) atoms to form a mixture of edge and corner-sharing NiO6 octahedra. The corner-sharing octahedral tilt angles are 53°. The Ni(2)-O(4) bond length is 1.82 Å. The Ni(2)-O(8) bond length is 1.95 Å. Both Ni(2)-O(3) bond lengths are 1.88 Å. Both Ni(2)-O(6) bond lengths are 2.02 Å. In the third Ni site, Ni(3) is bonded to one O(1), one O(6), two equivalent O(2), and two equivalent O(8) atoms to form a mixture of edge and corner-sharing NiO6 octahedra. The corner-sharing octahedral tilt angles are 53°. The Ni(3)-O(1) bond length is 1.82 Å. The Ni(3)-O(6) bond length is 1.95 Å. Both Ni(3)-O(2) bond lengths are 1.88 Å. There is one shorter (2.01 Å) and one longer (2.02 Å) Ni(3)-O(8) bond length. In the fourth Ni site, Ni(4) is bonded to one O(3), one O(5), two equivalent O(1), and two equivalent O(7) atoms to form a mixture of edge and corner-sharing NiO6 octahedra. The corner-sharing octahedral tilt angles are 53°. The Ni(4)-O(3) bond length is 1.82 Å. The Ni(4)-O(5) bond length is 1.95 Å. Both Ni(4)-O(1) bond lengths are 1.88 Å. Both Ni(4)-O(7) bond lengths are 2.01 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Ni(3) and two equivalent Ni(4) atoms. In the second O site, O(2) is bonded in a trigonal planar geometry to one Ni(1) and two equivalent Ni(3) atoms. In the third O site, O(3) is bonded in a trigonal planar geometry to one Ni(4) and two equivalent Ni(2) atoms. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Ni(2) and two equivalent Ni(1) atoms. In the fifth O site, O(5) is bonded to two equivalent Mg(1), one Ni(4), and two equivalent Ni(1) atoms to form a mixture of distorted edge and corner-sharing OMg2Ni3 trigonal bipyramids. In the sixth O site, O(6) is bonded to two equivalent Mg(1), one Ni(3), and two equivalent Ni(2) atoms to form a mixture of distorted edge and corner-sharing OMg2Ni3 trigonal bipyramids. In the seventh O site, O(7) is bonded to two equivalent Mg(1), one Ni(1), and two equivalent Ni(4) atoms to form a mixture of distorted edge and corner-sharing OMg2Ni3 trigonal bipyramids. In the eighth O site, O(8) is bonded to two equivalent Mg(1), one Ni(2), and two equivalent Ni(3) atoms to form a mixture of distorted edge and corner-sharing OMg2Ni3 trigonal bipyramids.