CaC4O4 crystallizes in the tetragonal I4_1/amd space group. Ca(1) is bonded to eight equivalent O(1) atoms to form distorted edge-sharing CaO8 hexagonal bipyramids. There are two inequivalent C sites. In the first C site, C(2) is bonded in a distorted bent 120 degrees geometry to one C(1) and two equivalent O(1) atoms. In the second C site, C(1) is bonded in a linear geometry to one C(1) and one C(2) atom. O(1) is bonded in a 3-coordinate geometry to two equivalent Ca(1) and one C(2) atom.
CaC4O4 crystallizes in the tetragonal I4_1/amd space group. Ca(1) is bonded to eight equivalent O(1) atoms to form distorted edge-sharing CaO8 hexagonal bipyramids. There are four shorter (2.38 Å) and four longer (2.73 Å) Ca(1)-O(1) bond lengths. There are two inequivalent C sites. In the first C site, C(2) is bonded in a distorted bent 120 degrees geometry to one C(1) and two equivalent O(1) atoms. The C(2)-C(1) bond length is 1.44 Å. Both C(2)-O(1) bond lengths are 1.27 Å. In the second C site, C(1) is bonded in a linear geometry to one C(1) and one C(2) atom. The C(1)-C(1) bond length is 1.22 Å. O(1) is bonded in a 3-coordinate geometry to two equivalent Ca(1) and one C(2) atom.