MgBe2(CoO2)4 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 Co(1)O6 octahedra and edges with six equivalent Co(2)O6 octahedra. The corner-sharing octahedral tilt angles are 7°. Be(1) is bonded in a 4-coordinate geometry to one O(2) and three equivalent O(1) atoms. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to six equivalent O(1) atoms to form CoO6 octahedra that share corners with six equivalent Mg(1)O6 octahedra and edges with six equivalent Co(2)O6 octahedra. The corner-sharing octahedral tilt angles are 7°. In the second Co site, Co(2) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form CoO6 octahedra that share edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, and edges with four equivalent Co(2)O6 octahedra. There are two inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), one Be(1), one Co(1), and two equivalent Co(2) atoms to form a mixture of distorted edge and corner-sharing OMgBeCo3 square pyramids. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Be(1) and three equivalent Co(2) atoms.
MgBe2(CoO2)4 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 Co(1)O6 octahedra and edges with six equivalent Co(2)O6 octahedra. The corner-sharing octahedral tilt angles are 7°. All Mg(1)-O(1) bond lengths are 2.04 Å. Be(1) is bonded in a 4-coordinate geometry to one O(2) and three equivalent O(1) atoms. The Be(1)-O(2) bond length is 1.55 Å. All Be(1)-O(1) bond lengths are 1.81 Å. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to six equivalent O(1) atoms to form CoO6 octahedra that share corners with six equivalent Mg(1)O6 octahedra and edges with six equivalent Co(2)O6 octahedra. The corner-sharing octahedral tilt angles are 7°. All Co(1)-O(1) bond lengths are 2.06 Å. In the second Co site, Co(2) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form CoO6 octahedra that share edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, and edges with four equivalent Co(2)O6 octahedra. Both Co(2)-O(2) bond lengths are 1.98 Å. All Co(2)-O(1) bond lengths are 2.14 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), one Be(1), one Co(1), and two equivalent Co(2) atoms to form a mixture of distorted edge and corner-sharing OMgBeCo3 square pyramids. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Be(1) and three equivalent Co(2) atoms.