Ba4Mg(CuO2)4 crystallizes in the triclinic P1 space group. There are four inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 6-coordinate geometry to two equivalent O(2), two equivalent O(4), and two equivalent O(8) atoms. In the second Ba site, Ba(2) is bonded in a 6-coordinate geometry to two equivalent O(3), two equivalent O(6), and two equivalent O(7) atoms. In the third Ba site, Ba(3) is bonded in a 5-coordinate geometry to one O(5), two equivalent O(1), and two equivalent O(8) atoms. In the fourth Ba site, Ba(4) is bonded in a 5-coordinate geometry to one O(1), two equivalent O(5), and two equivalent O(7) atoms. Mg(1) is bonded in a rectangular see-saw-like geometry to one O(2), one O(3), one O(4), and one O(6) atom. There are four inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a linear geometry to one O(5) and one O(8) atom. In the second Cu site, Cu(2) is bonded in a linear geometry to one O(1) and one O(7) atom. In the third Cu site, Cu(3) is bonded in a T-shaped geometry to one O(2), one O(4), and one O(6) atom. In the fourth Cu site, Cu(4) is bonded in a T-shaped geometry to one O(2), one O(3), and one O(6) atom. There are eight inequivalent O sites. In the first O site, O(1) is bonded to one Ba(4), two equivalent Ba(3), and one Cu(2) atom to form a mixture of distorted corner and edge-sharing OBa3Cu tetrahedra. In the second O site, O(2) is bonded in a 5-coordinate geometry to two equivalent Ba(1), one Mg(1), one Cu(3), and one Cu(4) atom. In the third O site, O(3) is bonded to two equivalent Ba(2), one Mg(1), and one Cu(4) atom to form distorted corner-sharing OBa2MgCu trigonal pyramids. In the fourth O site, O(4) is bonded to two equivalent Ba(1), one Mg(1), and one Cu(3) atom to form distorted corner-sharing OBa2MgCu trigonal pyramids. In the fifth O site, O(5) is bonded to one Ba(3), two equivalent Ba(4), and one Cu(1) atom to form a mixture of distorted corner and edge-sharing OBa3Cu tetrahedra. In the sixth O site, O(6) is bonded in a 5-coordinate geometry to two equivalent Ba(2), one Mg(1), one Cu(3), and one Cu(4) atom. In the seventh O site, O(7) is bonded in a 5-coordinate geometry to two equivalent Ba(2), two equivalent Ba(4), and one Cu(2) atom. In the eighth O site, O(8) is bonded in a 5-coordinate geometry to two equivalent Ba(1), two equivalent Ba(3), and one Cu(1) atom.
Ba4Mg(CuO2)4 crystallizes in the triclinic P1 space group. There are four inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 6-coordinate geometry to two equivalent O(2), two equivalent O(4), and two equivalent O(8) atoms. There is one shorter (2.77 Å) and one longer (3.26 Å) Ba(1)-O(2) bond length. There is one shorter (2.64 Å) and one longer (2.78 Å) Ba(1)-O(4) bond length. There is one shorter (2.70 Å) and one longer (2.77 Å) Ba(1)-O(8) bond length. In the second Ba site, Ba(2) is bonded in a 6-coordinate geometry to two equivalent O(3), two equivalent O(6), and two equivalent O(7) atoms. There is one shorter (2.64 Å) and one longer (2.78 Å) Ba(2)-O(3) bond length. There is one shorter (2.77 Å) and one longer (3.24 Å) Ba(2)-O(6) bond length. There is one shorter (2.70 Å) and one longer (2.76 Å) Ba(2)-O(7) bond length. In the third Ba site, Ba(3) is bonded in a 5-coordinate geometry to one O(5), two equivalent O(1), and two equivalent O(8) atoms. The Ba(3)-O(5) bond length is 2.56 Å. There is one shorter (2.60 Å) and one longer (2.64 Å) Ba(3)-O(1) bond length. There is one shorter (2.85 Å) and one longer (2.89 Å) Ba(3)-O(8) bond length. In the fourth Ba site, Ba(4) is bonded in a 5-coordinate geometry to one O(1), two equivalent O(5), and two equivalent O(7) atoms. The Ba(4)-O(1) bond length is 2.56 Å. There is one shorter (2.60 Å) and one longer (2.64 Å) Ba(4)-O(5) bond length. There is one shorter (2.85 Å) and one longer (2.89 Å) Ba(4)-O(7) bond length. Mg(1) is bonded in a rectangular see-saw-like geometry to one O(2), one O(3), one O(4), and one O(6) atom. The Mg(1)-O(2) bond length is 2.05 Å. The Mg(1)-O(3) bond length is 1.97 Å. The Mg(1)-O(4) bond length is 1.97 Å. The Mg(1)-O(6) bond length is 2.05 Å. There are four inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a linear geometry to one O(5) and one O(8) atom. The Cu(1)-O(5) bond length is 1.78 Å. The Cu(1)-O(8) bond length is 1.81 Å. In the second Cu site, Cu(2) is bonded in a linear geometry to one O(1) and one O(7) atom. The Cu(2)-O(1) bond length is 1.78 Å. The Cu(2)-O(7) bond length is 1.81 Å. In the third Cu site, Cu(3) is bonded in a T-shaped geometry to one O(2), one O(4), and one O(6) atom. The Cu(3)-O(2) bond length is 1.83 Å. The Cu(3)-O(4) bond length is 1.84 Å. The Cu(3)-O(6) bond length is 2.10 Å. In the fourth Cu site, Cu(4) is bonded in a T-shaped geometry to one O(2), one O(3), and one O(6) atom. The Cu(4)-O(2) bond length is 2.10 Å. The Cu(4)-O(3) bond length is 1.84 Å. The Cu(4)-O(6) bond length is 1.83 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded to one Ba(4), two equivalent Ba(3), and one Cu(2) atom to form a mixture of distorted corner and edge-sharing OBa3Cu tetrahedra. In the second O site, O(2) is bonded in a 5-coordinate geometry to two equivalent Ba(1), one Mg(1), one Cu(3), and one Cu(4) atom. In the third O site, O(3) is bonded to two equivalent Ba(2), one Mg(1), and one Cu(4) atom to form distorted corner-sharing OBa2MgCu trigonal pyramids. In the fourth O site, O(4) is bonded to two equivalent Ba(1), one Mg(1), and one Cu(3) atom to form distorted corner-sharing OBa2MgCu trigonal pyramids. In the fifth O site, O(5) is bonded to one Ba(3), two equivalent Ba(4), and one Cu(1) atom to form a mixture of distorted corner and edge-sharing OBa3Cu tetrahedra. In the sixth O site, O(6) is bonded in a 5-coordinate geometry to two equivalent Ba(2), one Mg(1), one Cu(3), and one Cu(4) atom. In the seventh O site, O(7) is bonded in a 5-coordinate geometry to two equivalent Ba(2), two equivalent Ba(4), and one Cu(2) atom. In the eighth O site, O(8) is bonded in a 5-coordinate geometry to two equivalent Ba(1), two equivalent Ba(3), and one Cu(1) atom.