Ba2Cu2O5 crystallizes in the orthorhombic Pna2_1 space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 6-coordinate geometry to one O(2), one O(3), two equivalent O(1), and two equivalent O(5) atoms. In the second Ba site, Ba(2) is bonded in a 6-coordinate geometry to one O(3), one O(5), two equivalent O(2), and two equivalent O(4) atoms. 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 Ba(1), one Cu(1), and one Cu(2) atom to form distorted OBa2Cu2 tetrahedra that share corners with two equivalent O(1)Ba2Cu2 tetrahedra, corners with three equivalent O(5)Ba3Cu tetrahedra, corners with three equivalent O(2)Ba3Cu trigonal pyramids,  an edgeedge with one O(5)Ba3Cu tetrahedra, and  an edgeedge with one O(4)Ba2Cu2 trigonal pyramid. In the second O site, O(2) is bonded to one Ba(1), two equivalent Ba(2), and one Cu(1) atom to form distorted OBa3Cu trigonal pyramids that share corners with three equivalent O(1)Ba2Cu2 tetrahedra, corners with four equivalent O(5)Ba3Cu tetrahedra, corners with two equivalent O(2)Ba3Cu trigonal pyramids, corners with three equivalent O(4)Ba2Cu2 trigonal pyramids, and  an edgeedge with one O(4)Ba2Cu2 trigonal pyramid. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Ba(1), one Ba(2), one Cu(1), and one Cu(2) atom. In the fourth O site, O(4) is bonded to two equivalent Ba(2), one Cu(1), and one Cu(2) atom to form distorted OBa2Cu2 trigonal pyramids that share corners with three equivalent O(5)Ba3Cu tetrahedra, corners with two equivalent O(4)Ba2Cu2 trigonal pyramids, corners with three equivalent O(2)Ba3Cu trigonal pyramids,  an edgeedge with one O(1)Ba2Cu2 tetrahedra, and  an edgeedge with one O(2)Ba3Cu trigonal pyramid. In the fifth O site, O(5) is bonded to one Ba(2), two equivalent Ba(1), and one Cu(2) atom to form distorted OBa3Cu tetrahedra that share corners with two equivalent O(5)Ba3Cu tetrahedra, corners with three equivalent O(1)Ba2Cu2 tetrahedra, corners with three equivalent O(4)Ba2Cu2 trigonal pyramids, corners with four equivalent O(2)Ba3Cu trigonal pyramids, and  an edgeedge with one O(1)Ba2Cu2 tetrahedra.
Ba2Cu2O5 crystallizes in the orthorhombic Pna2_1 space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 6-coordinate geometry to one O(2), one O(3), two equivalent O(1), and two equivalent O(5) atoms. The Ba(1)-O(2) bond length is 2.62 Å. The Ba(1)-O(3) bond length is 2.67 Å. There is one shorter (2.72 Å) and one longer (2.77 Å) Ba(1)-O(1) bond length. There is one shorter (2.70 Å) and one longer (2.74 Å) Ba(1)-O(5) bond length. In the second Ba site, Ba(2) is bonded in a 6-coordinate geometry to one O(3), one O(5), two equivalent O(2), and two equivalent O(4) atoms. The Ba(2)-O(3) bond length is 2.66 Å. The Ba(2)-O(5) bond length is 2.59 Å. There is one shorter (2.71 Å) and one longer (2.73 Å) Ba(2)-O(2) bond length. There is one shorter (2.71 Å) and one longer (2.76 Å) Ba(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 1.82 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 Ba(1), one Cu(1), and one Cu(2) atom to form distorted OBa2Cu2 tetrahedra that share corners with two equivalent O(1)Ba2Cu2 tetrahedra, corners with three equivalent O(5)Ba3Cu tetrahedra, corners with three equivalent O(2)Ba3Cu trigonal pyramids,  an edgeedge with one O(5)Ba3Cu tetrahedra, and  an edgeedge with one O(4)Ba2Cu2 trigonal pyramid. In the second O site, O(2) is bonded to one Ba(1), two equivalent Ba(2), and one Cu(1) atom to form distorted OBa3Cu trigonal pyramids that share corners with three equivalent O(1)Ba2Cu2 tetrahedra, corners with four equivalent O(5)Ba3Cu tetrahedra, corners with two equivalent O(2)Ba3Cu trigonal pyramids, corners with three equivalent O(4)Ba2Cu2 trigonal pyramids, and  an edgeedge with one O(4)Ba2Cu2 trigonal pyramid. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Ba(1), one Ba(2), one Cu(1), and one Cu(2) atom. In the fourth O site, O(4) is bonded to two equivalent Ba(2), one Cu(1), and one Cu(2) atom to form distorted OBa2Cu2 trigonal pyramids that share corners with three equivalent O(5)Ba3Cu tetrahedra, corners with two equivalent O(4)Ba2Cu2 trigonal pyramids, corners with three equivalent O(2)Ba3Cu trigonal pyramids,  an edgeedge with one O(1)Ba2Cu2 tetrahedra, and  an edgeedge with one O(2)Ba3Cu trigonal pyramid. In the fifth O site, O(5) is bonded to one Ba(2), two equivalent Ba(1), and one Cu(2) atom to form distorted OBa3Cu tetrahedra that share corners with two equivalent O(5)Ba3Cu tetrahedra, corners with three equivalent O(1)Ba2Cu2 tetrahedra, corners with three equivalent O(4)Ba2Cu2 trigonal pyramids, corners with four equivalent O(2)Ba3Cu trigonal pyramids, and  an edgeedge with one O(1)Ba2Cu2 tetrahedra.