CaCuO2 crystallizes in the triclinic P-1 space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 6-coordinate geometry to one O(1), one O(2), two equivalent O(3), and two equivalent O(4) atoms. In the second Ca site, Ca(2) is bonded in a 6-coordinate geometry to one O(1), two equivalent O(2), and three equivalent O(3) atoms. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a 3-coordinate geometry to one O(3), one O(4), and two equivalent O(1) atoms. In the second Cu site, Cu(2) is bonded in a rectangular see-saw-like geometry to one O(1), one O(2), and two equivalent O(4) atoms. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(2), one Cu(2), and two equivalent Cu(1) atoms. In the second O site, O(2) is bonded to one Ca(1), two equivalent Ca(2), and one Cu(2) atom to form OCa3Cu trigonal pyramids that share corners with two equivalent O(3)Ca5Cu octahedra, corners with two equivalent O(2)Ca3Cu trigonal pyramids, and edges with three equivalent O(3)Ca5Cu octahedra. The corner-sharing octahedral tilt angles range from 8-12°. In the third O site, O(3) is bonded to two equivalent Ca(1), three equivalent Ca(2), and one Cu(1) atom to form distorted OCa5Cu octahedra that share corners with two equivalent O(2)Ca3Cu trigonal pyramids, edges with four equivalent O(3)Ca5Cu octahedra, and edges with three equivalent O(2)Ca3Cu trigonal pyramids. In the fourth O site, O(4) is bonded in a 5-coordinate geometry to two equivalent Ca(1), one Cu(1), and two equivalent Cu(2) atoms.
CaCuO2 crystallizes in the triclinic P-1 space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 6-coordinate geometry to one O(1), one O(2), two equivalent O(3), and two equivalent O(4) atoms. The Ca(1)-O(1) bond length is 2.76 Å. The Ca(1)-O(2) bond length is 2.31 Å. There is one shorter (2.39 Å) and one longer (2.48 Å) Ca(1)-O(3) bond length. There is one shorter (2.26 Å) and one longer (2.34 Å) Ca(1)-O(4) bond length. In the second Ca site, Ca(2) is bonded in a 6-coordinate geometry to one O(1), two equivalent O(2), and three equivalent O(3) atoms. The Ca(2)-O(1) bond length is 2.73 Å. There is one shorter (2.28 Å) and one longer (2.32 Å) Ca(2)-O(2) bond length. There are a spread of Ca(2)-O(3) bond distances ranging from 2.42-2.68 Å. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a 3-coordinate geometry to one O(3), one O(4), and two equivalent O(1) atoms. The Cu(1)-O(3) bond length is 1.97 Å. The Cu(1)-O(4) bond length is 2.57 Å. There is one shorter (1.88 Å) and one longer (1.91 Å) Cu(1)-O(1) bond length. In the second Cu site, Cu(2) is bonded in a rectangular see-saw-like geometry to one O(1), one O(2), and two equivalent O(4) atoms. The Cu(2)-O(1) bond length is 1.91 Å. The Cu(2)-O(2) bond length is 1.85 Å. There is one shorter (1.88 Å) and one longer (1.98 Å) Cu(2)-O(4) bond length. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(2), one Cu(2), and two equivalent Cu(1) atoms. In the second O site, O(2) is bonded to one Ca(1), two equivalent Ca(2), and one Cu(2) atom to form OCa3Cu trigonal pyramids that share corners with two equivalent O(3)Ca5Cu octahedra, corners with two equivalent O(2)Ca3Cu trigonal pyramids, and edges with three equivalent O(3)Ca5Cu octahedra. The corner-sharing octahedral tilt angles range from 8-12°. In the third O site, O(3) is bonded to two equivalent Ca(1), three equivalent Ca(2), and one Cu(1) atom to form distorted OCa5Cu octahedra that share corners with two equivalent O(2)Ca3Cu trigonal pyramids, edges with four equivalent O(3)Ca5Cu octahedra, and edges with three equivalent O(2)Ca3Cu trigonal pyramids. In the fourth O site, O(4) is bonded in a 5-coordinate geometry to two equivalent Ca(1), one Cu(1), and two equivalent Cu(2) atoms.