BaCu4O7 crystallizes in the hexagonal P6_3mc space group. Ba(1) is bonded to six equivalent O(1) and six equivalent O(3) atoms to form distorted BaO12 cuboctahedra that share corners with twelve equivalent Ba(1)O12 cuboctahedra, edges with three equivalent Cu(2)O4 tetrahedra, and edges with nine equivalent Cu(1)O4 tetrahedra. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form CuO4 tetrahedra that share corners with two equivalent Cu(2)O4 tetrahedra, corners with four equivalent Cu(1)O4 tetrahedra, and edges with three equivalent Ba(1)O12 cuboctahedra. In the second Cu site, Cu(2) is bonded to one O(2) and three equivalent O(1) atoms to form CuO4 tetrahedra that share corners with six equivalent Cu(1)O4 tetrahedra and edges with three equivalent Ba(1)O12 cuboctahedra. There are three inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to two equivalent Ba(1), one Cu(1), and one Cu(2) atom. In the second O site, O(2) is bonded in a tetrahedral geometry to one Cu(2) and three equivalent Cu(1) atoms. In the third O site, O(3) is bonded in a distorted bent 120 degrees geometry to two equivalent Ba(1) and two equivalent Cu(1) atoms.
BaCu4O7 crystallizes in the hexagonal P6_3mc space group. Ba(1) is bonded to six equivalent O(1) and six equivalent O(3) atoms to form distorted BaO12 cuboctahedra that share corners with twelve equivalent Ba(1)O12 cuboctahedra, edges with three equivalent Cu(2)O4 tetrahedra, and edges with nine equivalent Cu(1)O4 tetrahedra. All Ba(1)-O(1) bond lengths are 3.21 Å. There are three shorter (2.95 Å) and three longer (3.39 Å) Ba(1)-O(3) bond lengths. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form CuO4 tetrahedra that share corners with two equivalent Cu(2)O4 tetrahedra, corners with four equivalent Cu(1)O4 tetrahedra, and edges with three equivalent Ba(1)O12 cuboctahedra. The Cu(1)-O(1) bond length is 1.84 Å. The Cu(1)-O(2) bond length is 1.99 Å. Both Cu(1)-O(3) bond lengths are 1.86 Å. In the second Cu site, Cu(2) is bonded to one O(2) and three equivalent O(1) atoms to form CuO4 tetrahedra that share corners with six equivalent Cu(1)O4 tetrahedra and edges with three equivalent Ba(1)O12 cuboctahedra. The Cu(2)-O(2) bond length is 1.91 Å. All Cu(2)-O(1) bond lengths are 1.85 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to two equivalent Ba(1), one Cu(1), and one Cu(2) atom. In the second O site, O(2) is bonded in a tetrahedral geometry to one Cu(2) and three equivalent Cu(1) atoms. In the third O site, O(3) is bonded in a distorted bent 120 degrees geometry to two equivalent Ba(1) and two equivalent Cu(1) atoms.