BaCa(CoO2)4 crystallizes in the trigonal P-31m space group. Ba(1) is bonded to six equivalent O(1) and six equivalent O(2) atoms to form BaO12 cuboctahedra that share edges with six equivalent Ba(1)O12 cuboctahedra, edges with twelve equivalent Co(1)O4 tetrahedra, and faces with two equivalent Ca(1)O6 octahedra. Ca(1) is bonded to six equivalent O(1) atoms to form CaO6 octahedra that share corners with twelve equivalent Co(1)O4 tetrahedra and faces with two equivalent Ba(1)O12 cuboctahedra. Co(1) is bonded to one O(2) and three equivalent O(1) atoms to form CoO4 tetrahedra that share corners with three equivalent Ca(1)O6 octahedra, corners with four equivalent Co(1)O4 tetrahedra, and edges with three equivalent Ba(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 57°. There are two inequivalent O sites. In the first O site, O(1) is bonded to one Ba(1), one Ca(1), and two equivalent Co(1) atoms to form a mixture of distorted corner and edge-sharing OBaCaCo2 trigonal pyramids. In the second O site, O(2) is bonded in a linear geometry to three equivalent Ba(1) and two equivalent Co(1) atoms.
BaCa(CoO2)4 crystallizes in the trigonal P-31m space group. Ba(1) is bonded to six equivalent O(1) and six equivalent O(2) atoms to form BaO12 cuboctahedra that share edges with six equivalent Ba(1)O12 cuboctahedra, edges with twelve equivalent Co(1)O4 tetrahedra, and faces with two equivalent Ca(1)O6 octahedra. All Ba(1)-O(1) bond lengths are 2.97 Å. All Ba(1)-O(2) bond lengths are 3.13 Å. Ca(1) is bonded to six equivalent O(1) atoms to form CaO6 octahedra that share corners with twelve equivalent Co(1)O4 tetrahedra and faces with two equivalent Ba(1)O12 cuboctahedra. All Ca(1)-O(1) bond lengths are 2.39 Å. Co(1) is bonded to one O(2) and three equivalent O(1) atoms to form CoO4 tetrahedra that share corners with three equivalent Ca(1)O6 octahedra, corners with four equivalent Co(1)O4 tetrahedra, and edges with three equivalent Ba(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 57°. The Co(1)-O(2) bond length is 1.84 Å. All Co(1)-O(1) bond lengths are 1.88 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded to one Ba(1), one Ca(1), and two equivalent Co(1) atoms to form a mixture of distorted corner and edge-sharing OBaCaCo2 trigonal pyramids. In the second O site, O(2) is bonded in a linear geometry to three equivalent Ba(1) and two equivalent Co(1) atoms.