CaCuBiO5 crystallizes in the monoclinic P2_1/c space group. Ca(1) is bonded to one O(1), one O(2), one O(3), one O(5), and two equivalent O(4) atoms to form distorted CaO6 pentagonal pyramids that share corners with two equivalent Bi(1)O6 octahedra, edges with three equivalent Bi(1)O6 octahedra, and  an edgeedge with one Ca(1)O6 pentagonal pyramid. The corner-sharing octahedral tilt angles range from 36-41°. Cu(1) is bonded in a distorted rectangular see-saw-like geometry to one O(1), one O(2), one O(3), and one O(5) atom. Bi(1) is bonded to one O(1), one O(2), one O(3), one O(5), and two equivalent O(4) atoms to form distorted BiO6 octahedra that share corners with two equivalent Ca(1)O6 pentagonal pyramids,  an edgeedge with one Bi(1)O6 octahedra, and edges with three equivalent Ca(1)O6 pentagonal pyramids. There are five inequivalent O sites. In the first O site, O(1) is bonded in a trigonal non-coplanar geometry to one Ca(1), one Cu(1), and one Bi(1) atom. In the second O site, O(2) is bonded in a distorted trigonal non-coplanar geometry to one Ca(1), one Cu(1), and one Bi(1) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Ca(1), one Cu(1), and one Bi(1) atom. In the fourth O site, O(4) is bonded to two equivalent Ca(1) and two equivalent Bi(1) atoms to form distorted edge-sharing OCa2Bi2 tetrahedra. In the fifth O site, O(5) is bonded in a distorted trigonal non-coplanar geometry to one Ca(1), one Cu(1), and one Bi(1) atom.
CaCuBiO5 crystallizes in the monoclinic P2_1/c space group. Ca(1) is bonded to one O(1), one O(2), one O(3), one O(5), and two equivalent O(4) atoms to form distorted CaO6 pentagonal pyramids that share corners with two equivalent Bi(1)O6 octahedra, edges with three equivalent Bi(1)O6 octahedra, and  an edgeedge with one Ca(1)O6 pentagonal pyramid. The corner-sharing octahedral tilt angles range from 36-41°. The Ca(1)-O(1) bond length is 2.31 Å. The Ca(1)-O(2) bond length is 2.48 Å. The Ca(1)-O(3) bond length is 2.38 Å. The Ca(1)-O(5) bond length is 2.30 Å. There is one shorter (2.39 Å) and one longer (2.54 Å) Ca(1)-O(4) bond length. Cu(1) is bonded in a distorted rectangular see-saw-like geometry to one O(1), one O(2), one O(3), and one O(5) atom. The Cu(1)-O(1) bond length is 1.86 Å. The Cu(1)-O(2) bond length is 1.88 Å. The Cu(1)-O(3) bond length is 1.87 Å. The Cu(1)-O(5) bond length is 1.81 Å. Bi(1) is bonded to one O(1), one O(2), one O(3), one O(5), and two equivalent O(4) atoms to form distorted BiO6 octahedra that share corners with two equivalent Ca(1)O6 pentagonal pyramids,  an edgeedge with one Bi(1)O6 octahedra, and edges with three equivalent Ca(1)O6 pentagonal pyramids. The Bi(1)-O(1) bond length is 2.17 Å. The Bi(1)-O(2) bond length is 2.13 Å. The Bi(1)-O(3) bond length is 2.17 Å. The Bi(1)-O(5) bond length is 2.16 Å. There is one shorter (2.19 Å) and one longer (2.21 Å) Bi(1)-O(4) bond length. There are five inequivalent O sites. In the first O site, O(1) is bonded in a trigonal non-coplanar geometry to one Ca(1), one Cu(1), and one Bi(1) atom. In the second O site, O(2) is bonded in a distorted trigonal non-coplanar geometry to one Ca(1), one Cu(1), and one Bi(1) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Ca(1), one Cu(1), and one Bi(1) atom. In the fourth O site, O(4) is bonded to two equivalent Ca(1) and two equivalent Bi(1) atoms to form distorted edge-sharing OCa2Bi2 tetrahedra. In the fifth O site, O(5) is bonded in a distorted trigonal non-coplanar geometry to one Ca(1), one Cu(1), and one Bi(1) atom.