Ba4Ca8Cu11CO20 crystallizes in the tetragonal I4/mmm space group. Ba(1) is bonded in a 4-coordinate geometry to two equivalent Cu(6), two equivalent C(1), and four equivalent O(1) atoms. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a body-centered cubic geometry to four equivalent O(1) and four equivalent O(3) atoms. In the second Ca site, Ca(2) is bonded in a body-centered cubic geometry to four equivalent O(2) and four equivalent O(3) atoms. There are six inequivalent Cu sites. In the first Cu site, Cu(5) is bonded in a rectangular see-saw-like geometry to four equivalent O(2) atoms. In the second Cu site, Cu(6) is bonded in a body-centered cubic geometry to eight equivalent Ba(1) atoms. In the third Cu site, Cu(1) is bonded in a rectangular see-saw-like geometry to four equivalent O(3) atoms. In the fourth Cu site, Cu(2) is bonded in a rectangular see-saw-like geometry to four equivalent O(3) atoms. In the fifth Cu site, Cu(3) is bonded in a rectangular see-saw-like geometry to four equivalent O(1) atoms. In the sixth Cu site, Cu(4) is bonded in a rectangular see-saw-like geometry to four equivalent O(1) atoms. C(1) is bonded in a body-centered cubic geometry to eight equivalent Ba(1) atoms. There are three inequivalent O sites. In the first O site, O(3) is bonded to two equivalent Ca(1), two equivalent Ca(2), one Cu(1), and one Cu(2) atom to form OCa4Cu2 octahedra that share corners with two equivalent O(3)Ca4Cu2 octahedra, corners with six equivalent O(1)Ba2Ca2Cu2 octahedra, corners with six equivalent O(2)Ca4Cu2 octahedra,  an edgeedge with one O(1)Ba2Ca2Cu2 octahedra,  an edgeedge with one O(2)Ca4Cu2 octahedra, edges with two equivalent O(3)Ca4Cu2 octahedra, and faces with four equivalent O(3)Ca4Cu2 octahedra. The corner-sharing octahedral tilt angles range from 1-67°. In the second O site, O(1) is bonded to two equivalent Ba(1), two equivalent Ca(1), one Cu(3), and one Cu(4) atom to form OBa2Ca2Cu2 octahedra that share corners with two equivalent O(1)Ba2Ca2Cu2 octahedra, corners with six equivalent O(3)Ca4Cu2 octahedra,  an edgeedge with one O(3)Ca4Cu2 octahedra, edges with two equivalent O(1)Ba2Ca2Cu2 octahedra, and faces with four equivalent O(1)Ba2Ca2Cu2 octahedra. The corner-sharing octahedral tilt angles range from 3-67°. In the third O site, O(2) is bonded to four equivalent Ca(2) and two equivalent Cu(5) atoms to form a mixture of corner, edge, and face-sharing OCa4Cu2 octahedra. The corner-sharing octahedral tilt angles range from 0-67°.
Ba4Ca8Cu11CO20 crystallizes in the tetragonal I4/mmm space group. Ba(1) is bonded in a 4-coordinate geometry to two equivalent Cu(6), two equivalent C(1), and four equivalent O(1) atoms. Both Ba(1)-Cu(6) bond lengths are 3.56 Å. Both Ba(1)-C(1) bond lengths are 3.56 Å. All Ba(1)-O(1) bond lengths are 2.65 Å. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a body-centered cubic geometry to four equivalent O(1) and four equivalent O(3) atoms. All Ca(1)-O(1) bond lengths are 2.58 Å. All Ca(1)-O(3) bond lengths are 2.49 Å. In the second Ca site, Ca(2) is bonded in a body-centered cubic geometry to four equivalent O(2) and four equivalent O(3) atoms. All Ca(2)-O(2) bond lengths are 2.51 Å. All Ca(2)-O(3) bond lengths are 2.54 Å. There are six inequivalent Cu sites. In the first Cu site, Cu(5) is bonded in a rectangular see-saw-like geometry to four equivalent O(2) atoms. All Cu(5)-O(2) bond lengths are 1.96 Å. In the second Cu site, Cu(6) is bonded in a body-centered cubic geometry to eight equivalent Ba(1) atoms. In the third Cu site, Cu(1) is bonded in a rectangular see-saw-like geometry to four equivalent O(3) atoms. All Cu(1)-O(3) bond lengths are 1.96 Å. In the fourth Cu site, Cu(2) is bonded in a rectangular see-saw-like geometry to four equivalent O(3) atoms. All Cu(2)-O(3) bond lengths are 1.97 Å. In the fifth Cu site, Cu(3) is bonded in a rectangular see-saw-like geometry to four equivalent O(1) atoms. All Cu(3)-O(1) bond lengths are 1.97 Å. In the sixth Cu site, Cu(4) is bonded in a rectangular see-saw-like geometry to four equivalent O(1) atoms. All Cu(4)-O(1) bond lengths are 1.97 Å. C(1) is bonded in a body-centered cubic geometry to eight equivalent Ba(1) atoms. There are three inequivalent O sites. In the first O site, O(3) is bonded to two equivalent Ca(1), two equivalent Ca(2), one Cu(1), and one Cu(2) atom to form OCa4Cu2 octahedra that share corners with two equivalent O(3)Ca4Cu2 octahedra, corners with six equivalent O(1)Ba2Ca2Cu2 octahedra, corners with six equivalent O(2)Ca4Cu2 octahedra,  an edgeedge with one O(1)Ba2Ca2Cu2 octahedra,  an edgeedge with one O(2)Ca4Cu2 octahedra, edges with two equivalent O(3)Ca4Cu2 octahedra, and faces with four equivalent O(3)Ca4Cu2 octahedra. The corner-sharing octahedral tilt angles range from 1-67°. In the second O site, O(1) is bonded to two equivalent Ba(1), two equivalent Ca(1), one Cu(3), and one Cu(4) atom to form OBa2Ca2Cu2 octahedra that share corners with two equivalent O(1)Ba2Ca2Cu2 octahedra, corners with six equivalent O(3)Ca4Cu2 octahedra,  an edgeedge with one O(3)Ca4Cu2 octahedra, edges with two equivalent O(1)Ba2Ca2Cu2 octahedra, and faces with four equivalent O(1)Ba2Ca2Cu2 octahedra. The corner-sharing octahedral tilt angles range from 3-67°. In the third O site, O(2) is bonded to four equivalent Ca(2) and two equivalent Cu(5) atoms to form a mixture of corner, edge, and face-sharing OCa4Cu2 octahedra. The corner-sharing octahedral tilt angles range from 0-67°.