Ca2Cu2O5 crystallizes in the orthorhombic Pna2_1 space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one O(2), one O(3), two equivalent O(1), and two equivalent O(5) atoms to form a mixture of distorted corner and edge-sharing CaO6 pentagonal pyramids. The corner-sharing octahedral tilt angles range from 32-79°. In the second Ca site, Ca(2) is bonded to one O(3), one O(5), two equivalent O(2), and two equivalent O(4) atoms to form a mixture of distorted corner and edge-sharing CaO6 octahedra. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a rectangular see-saw-like geometry to one O(1), one O(2), one O(3), and one O(4) atom. In the second Cu site, Cu(2) is bonded in a rectangular see-saw-like geometry to one O(1), one O(3), one O(4), and one O(5) atom. There are five inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Ca(1), one Cu(1), and one Cu(2) atom to form distorted OCa2Cu2 trigonal pyramids that share corners with two equivalent O(3)Ca2Cu2 tetrahedra, corners with three equivalent O(2)Ca3Cu tetrahedra, corners with three equivalent O(5)Ca3Cu tetrahedra, corners with two equivalent O(1)Ca2Cu2 trigonal pyramids,  an edgeedge with one O(3)Ca2Cu2 tetrahedra,  an edgeedge with one O(5)Ca3Cu tetrahedra, and  an edgeedge with one O(4)Ca2Cu2 trigonal pyramid. In the second O site, O(2) is bonded to one Ca(1), two equivalent Ca(2), and one Cu(1) atom to form distorted OCa3Cu tetrahedra that share corners with two equivalent O(3)Ca2Cu2 tetrahedra, corners with two equivalent O(2)Ca3Cu tetrahedra, corners with four equivalent O(5)Ca3Cu tetrahedra, corners with three equivalent O(1)Ca2Cu2 trigonal pyramids, corners with three equivalent O(4)Ca2Cu2 trigonal pyramids,  an edgeedge with one O(3)Ca2Cu2 tetrahedra, and  an edgeedge with one O(4)Ca2Cu2 trigonal pyramid. In the third O site, O(3) is bonded to one Ca(1), one Ca(2), one Cu(1), and one Cu(2) atom to form distorted OCa2Cu2 tetrahedra that share corners with two equivalent O(2)Ca3Cu tetrahedra, corners with two equivalent O(5)Ca3Cu tetrahedra, corners with two equivalent O(1)Ca2Cu2 trigonal pyramids, corners with two equivalent O(4)Ca2Cu2 trigonal pyramids,  an edgeedge with one O(2)Ca3Cu tetrahedra,  an edgeedge with one O(5)Ca3Cu tetrahedra,  an edgeedge with one O(1)Ca2Cu2 trigonal pyramid, and  an edgeedge with one O(4)Ca2Cu2 trigonal pyramid. In the fourth O site, O(4) is bonded to two equivalent Ca(2), one Cu(1), and one Cu(2) atom to form distorted OCa2Cu2 trigonal pyramids that share corners with two equivalent O(3)Ca2Cu2 tetrahedra, corners with three equivalent O(2)Ca3Cu tetrahedra, corners with three equivalent O(5)Ca3Cu tetrahedra, corners with two equivalent O(4)Ca2Cu2 trigonal pyramids,  an edgeedge with one O(3)Ca2Cu2 tetrahedra,  an edgeedge with one O(2)Ca3Cu tetrahedra, and  an edgeedge with one O(1)Ca2Cu2 trigonal pyramid. In the fifth O site, O(5) is bonded to one Ca(2), two equivalent Ca(1), and one Cu(2) atom to form OCa3Cu tetrahedra that share corners with two equivalent O(3)Ca2Cu2 tetrahedra, corners with two equivalent O(5)Ca3Cu tetrahedra, corners with four equivalent O(2)Ca3Cu tetrahedra, corners with three equivalent O(1)Ca2Cu2 trigonal pyramids, corners with three equivalent O(4)Ca2Cu2 trigonal pyramids,  an edgeedge with one O(3)Ca2Cu2 tetrahedra, and  an edgeedge with one O(1)Ca2Cu2 trigonal pyramid.
Ca2Cu2O5 crystallizes in the orthorhombic Pna2_1 space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one O(2), one O(3), two equivalent O(1), and two equivalent O(5) atoms to form a mixture of distorted corner and edge-sharing CaO6 pentagonal pyramids. The corner-sharing octahedral tilt angles range from 32-79°. The Ca(1)-O(2) bond length is 2.28 Å. The Ca(1)-O(3) bond length is 2.37 Å. There is one shorter (2.41 Å) and one longer (2.47 Å) Ca(1)-O(1) bond length. There is one shorter (2.32 Å) and one longer (2.34 Å) Ca(1)-O(5) bond length. In the second Ca site, Ca(2) is bonded to one O(3), one O(5), two equivalent O(2), and two equivalent O(4) atoms to form a mixture of distorted corner and edge-sharing CaO6 octahedra. The Ca(2)-O(3) bond length is 2.36 Å. The Ca(2)-O(5) bond length is 2.26 Å. There is one shorter (2.33 Å) and one longer (2.34 Å) Ca(2)-O(2) bond length. There is one shorter (2.38 Å) and one longer (2.47 Å) Ca(2)-O(4) bond length. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a rectangular see-saw-like geometry to one O(1), one O(2), one O(3), and one O(4) atom. The Cu(1)-O(1) bond length is 1.85 Å. The Cu(1)-O(2) bond length is 1.82 Å. The Cu(1)-O(3) bond length is 1.83 Å. The Cu(1)-O(4) bond length is 1.83 Å. In the second Cu site, Cu(2) is bonded in a rectangular see-saw-like geometry to one O(1), one O(3), one O(4), and one O(5) atom. The Cu(2)-O(1) bond length is 1.83 Å. The Cu(2)-O(3) bond length is 1.83 Å. The Cu(2)-O(4) bond length is 1.86 Å. The Cu(2)-O(5) bond length is 1.81 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Ca(1), one Cu(1), and one Cu(2) atom to form distorted OCa2Cu2 trigonal pyramids that share corners with two equivalent O(3)Ca2Cu2 tetrahedra, corners with three equivalent O(2)Ca3Cu tetrahedra, corners with three equivalent O(5)Ca3Cu tetrahedra, corners with two equivalent O(1)Ca2Cu2 trigonal pyramids,  an edgeedge with one O(3)Ca2Cu2 tetrahedra,  an edgeedge with one O(5)Ca3Cu tetrahedra, and  an edgeedge with one O(4)Ca2Cu2 trigonal pyramid. In the second O site, O(2) is bonded to one Ca(1), two equivalent Ca(2), and one Cu(1) atom to form distorted OCa3Cu tetrahedra that share corners with two equivalent O(3)Ca2Cu2 tetrahedra, corners with two equivalent O(2)Ca3Cu tetrahedra, corners with four equivalent O(5)Ca3Cu tetrahedra, corners with three equivalent O(1)Ca2Cu2 trigonal pyramids, corners with three equivalent O(4)Ca2Cu2 trigonal pyramids,  an edgeedge with one O(3)Ca2Cu2 tetrahedra, and  an edgeedge with one O(4)Ca2Cu2 trigonal pyramid. In the third O site, O(3) is bonded to one Ca(1), one Ca(2), one Cu(1), and one Cu(2) atom to form distorted OCa2Cu2 tetrahedra that share corners with two equivalent O(2)Ca3Cu tetrahedra, corners with two equivalent O(5)Ca3Cu tetrahedra, corners with two equivalent O(1)Ca2Cu2 trigonal pyramids, corners with two equivalent O(4)Ca2Cu2 trigonal pyramids,  an edgeedge with one O(2)Ca3Cu tetrahedra,  an edgeedge with one O(5)Ca3Cu tetrahedra,  an edgeedge with one O(1)Ca2Cu2 trigonal pyramid, and  an edgeedge with one O(4)Ca2Cu2 trigonal pyramid. In the fourth O site, O(4) is bonded to two equivalent Ca(2), one Cu(1), and one Cu(2) atom to form distorted OCa2Cu2 trigonal pyramids that share corners with two equivalent O(3)Ca2Cu2 tetrahedra, corners with three equivalent O(2)Ca3Cu tetrahedra, corners with three equivalent O(5)Ca3Cu tetrahedra, corners with two equivalent O(4)Ca2Cu2 trigonal pyramids,  an edgeedge with one O(3)Ca2Cu2 tetrahedra,  an edgeedge with one O(2)Ca3Cu tetrahedra, and  an edgeedge with one O(1)Ca2Cu2 trigonal pyramid. In the fifth O site, O(5) is bonded to one Ca(2), two equivalent Ca(1), and one Cu(2) atom to form OCa3Cu tetrahedra that share corners with two equivalent O(3)Ca2Cu2 tetrahedra, corners with two equivalent O(5)Ca3Cu tetrahedra, corners with four equivalent O(2)Ca3Cu tetrahedra, corners with three equivalent O(1)Ca2Cu2 trigonal pyramids, corners with three equivalent O(4)Ca2Cu2 trigonal pyramids,  an edgeedge with one O(3)Ca2Cu2 tetrahedra, and  an edgeedge with one O(1)Ca2Cu2 trigonal pyramid.