Ba2Mg(CoO3)2 crystallizes in the triclinic P1 space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 8-coordinate geometry to two equivalent Mg(1), two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms. In the second Ba site, Ba(2) is bonded to two equivalent O(1), two equivalent O(2), two equivalent O(3), two equivalent O(4), two equivalent O(5), and two equivalent O(6) atoms to form distorted BaO12 cuboctahedra that share corners with six equivalent Ba(2)O12 cuboctahedra, corners with three equivalent Co(1)O6 octahedra, corners with three equivalent Co(2)O6 octahedra, faces with two equivalent Ba(2)O12 cuboctahedra, faces with three equivalent Co(1)O6 octahedra, and faces with three equivalent Co(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 14-17°. Mg(1) is bonded in a trigonal planar geometry to two equivalent Ba(1), one O(2), one O(5), and one O(6) atom. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form distorted CoO6 octahedra that share corners with three equivalent Ba(2)O12 cuboctahedra, faces with three equivalent Ba(2)O12 cuboctahedra, and faces with two equivalent Co(2)O6 octahedra. In the second Co site, Co(2) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form distorted CoO6 octahedra that share corners with three equivalent Ba(2)O12 cuboctahedra, faces with three equivalent Ba(2)O12 cuboctahedra, and faces with two equivalent Co(1)O6 octahedra. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 2-coordinate geometry to two equivalent Ba(1), two equivalent Ba(2), one Co(1), and one Co(2) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to two equivalent Ba(2), one Mg(1), one Co(1), and one Co(2) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to two equivalent Ba(1), two equivalent Ba(2), one Co(1), and one Co(2) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to two equivalent Ba(1), two equivalent Ba(2), one Co(1), and one Co(2) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to two equivalent Ba(2), one Mg(1), one Co(1), and one Co(2) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to two equivalent Ba(2), one Mg(1), one Co(1), and one Co(2) atom.
Ba2Mg(CoO3)2 crystallizes in the triclinic P1 space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 8-coordinate geometry to two equivalent Mg(1), two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms. Both Ba(1)-Mg(1) bond lengths are 2.77 Å. There is one shorter (2.89 Å) and one longer (2.92 Å) Ba(1)-O(1) bond length. There is one shorter (2.87 Å) and one longer (2.99 Å) Ba(1)-O(3) bond length. There is one shorter (2.87 Å) and one longer (2.99 Å) Ba(1)-O(4) bond length. In the second Ba site, Ba(2) is bonded to two equivalent O(1), two equivalent O(2), two equivalent O(3), two equivalent O(4), two equivalent O(5), and two equivalent O(6) atoms to form distorted BaO12 cuboctahedra that share corners with six equivalent Ba(2)O12 cuboctahedra, corners with three equivalent Co(1)O6 octahedra, corners with three equivalent Co(2)O6 octahedra, faces with two equivalent Ba(2)O12 cuboctahedra, faces with three equivalent Co(1)O6 octahedra, and faces with three equivalent Co(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 14-17°. There is one shorter (3.31 Å) and one longer (3.32 Å) Ba(2)-O(1) bond length. There is one shorter (2.92 Å) and one longer (2.94 Å) Ba(2)-O(2) bond length. There is one shorter (3.31 Å) and one longer (3.35 Å) Ba(2)-O(3) bond length. There is one shorter (3.31 Å) and one longer (3.36 Å) Ba(2)-O(4) bond length. There is one shorter (2.93 Å) and one longer (2.94 Å) Ba(2)-O(5) bond length. There is one shorter (2.90 Å) and one longer (2.91 Å) Ba(2)-O(6) bond length. Mg(1) is bonded in a trigonal planar geometry to two equivalent Ba(1), one O(2), one O(5), and one O(6) atom. The Mg(1)-O(2) bond length is 1.84 Å. The Mg(1)-O(5) bond length is 1.84 Å. The Mg(1)-O(6) bond length is 1.83 Å. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form distorted CoO6 octahedra that share corners with three equivalent Ba(2)O12 cuboctahedra, faces with three equivalent Ba(2)O12 cuboctahedra, and faces with two equivalent Co(2)O6 octahedra. The Co(1)-O(1) bond length is 2.04 Å. The Co(1)-O(2) bond length is 2.13 Å. The Co(1)-O(3) bond length is 2.14 Å. The Co(1)-O(4) bond length is 1.87 Å. The Co(1)-O(5) bond length is 2.09 Å. The Co(1)-O(6) bond length is 2.14 Å. In the second Co site, Co(2) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form distorted CoO6 octahedra that share corners with three equivalent Ba(2)O12 cuboctahedra, faces with three equivalent Ba(2)O12 cuboctahedra, and faces with two equivalent Co(1)O6 octahedra. The Co(2)-O(1) bond length is 2.03 Å. The Co(2)-O(2) bond length is 2.11 Å. The Co(2)-O(3) bond length is 1.88 Å. The Co(2)-O(4) bond length is 2.13 Å. The Co(2)-O(5) bond length is 2.11 Å. The Co(2)-O(6) bond length is 2.14 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 2-coordinate geometry to two equivalent Ba(1), two equivalent Ba(2), one Co(1), and one Co(2) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to two equivalent Ba(2), one Mg(1), one Co(1), and one Co(2) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to two equivalent Ba(1), two equivalent Ba(2), one Co(1), and one Co(2) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to two equivalent Ba(1), two equivalent Ba(2), one Co(1), and one Co(2) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to two equivalent Ba(2), one Mg(1), one Co(1), and one Co(2) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to two equivalent Ba(2), one Mg(1), one Co(1), and one Co(2) atom.