Mg(NiO2)4 is beta indium sulfide-derived structured and crystallizes in the trigonal R-3m space group. Mg(1) is bonded to six equivalent O(1) atoms to form distorted MgO6 octahedra that share corners with six equivalent Ni(2)O6 octahedra and edges with six equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles are 14°. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to two equivalent O(2) and four equivalent O(1) 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. In the second Ni site, Ni(2) is bonded to six equivalent O(1) atoms to form NiO6 octahedra that share corners with six equivalent Mg(1)O6 octahedra and edges with six equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles are 14°. There are two inequivalent O sites. In the first O site, O(1) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Ni(2), and two equivalent Ni(1) atoms. In the second O site, O(2) is bonded in a distorted T-shaped geometry to three equivalent Ni(1) atoms.
Mg(NiO2)4 is beta indium sulfide-derived structured and crystallizes in the trigonal R-3m space group. Mg(1) is bonded to six equivalent O(1) atoms to form distorted MgO6 octahedra that share corners with six equivalent Ni(2)O6 octahedra and edges with six equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles are 14°. All Mg(1)-O(1) bond lengths are 2.10 Å. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to two equivalent O(2) and four equivalent O(1) 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(1)-O(2) bond lengths are 1.90 Å. All Ni(1)-O(1) bond lengths are 1.88 Å. In the second Ni site, Ni(2) is bonded to six equivalent O(1) atoms to form NiO6 octahedra that share corners with six equivalent Mg(1)O6 octahedra and edges with six equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles are 14°. All Ni(2)-O(1) bond lengths are 2.05 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Ni(2), and two equivalent Ni(1) atoms. In the second O site, O(2) is bonded in a distorted T-shaped geometry to three equivalent Ni(1) atoms.