Y2Cu2O5 crystallizes in the orthorhombic Pna2_1 space group. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded to one O(1), one O(3), two equivalent O(2), and two equivalent O(5) atoms to form a mixture of distorted edge and corner-sharing YO6 octahedra. The corner-sharing octahedral tilt angles range from 23-64°. In the second Y site, Y(2) is bonded to one O(3), one O(5), two equivalent O(1), and two equivalent O(4) atoms to form a mixture of edge and corner-sharing YO6 octahedra. The corner-sharing octahedral tilt angles range from 23-64°. 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(2), one O(3), one O(4), and one O(5) atom. In the second Cu site, Cu(2) is bonded in a rectangular see-saw-like geometry to one O(1), one O(2), one O(3), and one O(4) atom. There are five inequivalent O sites. In the first O site, O(5) is bonded to one Y(2), two equivalent Y(1), and one Cu(1) atom to form OY3Cu tetrahedra that share corners with two equivalent O(5)Y3Cu tetrahedra, corners with four equivalent O(1)Y3Cu tetrahedra, corners with three equivalent O(2)Y2Cu2 trigonal pyramids, corners with three equivalent O(4)Y2Cu2 trigonal pyramids, and  an edgeedge with one O(2)Y2Cu2 trigonal pyramid. In the second O site, O(1) is bonded to one Y(1), two equivalent Y(2), and one Cu(2) atom to form OY3Cu tetrahedra that share corners with two equivalent O(1)Y3Cu tetrahedra, corners with four equivalent O(5)Y3Cu tetrahedra, corners with three equivalent O(2)Y2Cu2 trigonal pyramids, corners with three equivalent O(4)Y2Cu2 trigonal pyramids, and  an edgeedge with one O(4)Y2Cu2 trigonal pyramid. In the third O site, O(2) is bonded to two equivalent Y(1), one Cu(1), and one Cu(2) atom to form distorted OY2Cu2 trigonal pyramids that share corners with three equivalent O(1)Y3Cu tetrahedra, corners with three equivalent O(5)Y3Cu tetrahedra, corners with two equivalent O(2)Y2Cu2 trigonal pyramids,  an edgeedge with one O(5)Y3Cu tetrahedra, and  an edgeedge with one O(4)Y2Cu2 trigonal pyramid. In the fourth O site, O(3) is bonded in a distorted see-saw-like geometry to one Y(1), one Y(2), one Cu(1), and one Cu(2) atom. In the fifth O site, O(4) is bonded to two equivalent Y(2), one Cu(1), and one Cu(2) atom to form OY2Cu2 trigonal pyramids that share corners with three equivalent O(1)Y3Cu tetrahedra, corners with three equivalent O(5)Y3Cu tetrahedra, corners with two equivalent O(4)Y2Cu2 trigonal pyramids,  an edgeedge with one O(1)Y3Cu tetrahedra, and  an edgeedge with one O(2)Y2Cu2 trigonal pyramid.
Y2Cu2O5 crystallizes in the orthorhombic Pna2_1 space group. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded to one O(1), one O(3), two equivalent O(2), and two equivalent O(5) atoms to form a mixture of distorted edge and corner-sharing YO6 octahedra. The corner-sharing octahedral tilt angles range from 23-64°. The Y(1)-O(1) bond length is 2.24 Å. The Y(1)-O(3) bond length is 2.29 Å. There is one shorter (2.32 Å) and one longer (2.33 Å) Y(1)-O(2) bond length. There is one shorter (2.30 Å) and one longer (2.32 Å) Y(1)-O(5) bond length. In the second Y site, Y(2) is bonded to one O(3), one O(5), two equivalent O(1), and two equivalent O(4) atoms to form a mixture of edge and corner-sharing YO6 octahedra. The corner-sharing octahedral tilt angles range from 23-64°. The Y(2)-O(3) bond length is 2.30 Å. The Y(2)-O(5) bond length is 2.24 Å. There is one shorter (2.29 Å) and one longer (2.33 Å) Y(2)-O(1) bond length. There is one shorter (2.32 Å) and one longer (2.33 Å) Y(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(2), one O(3), one O(4), and one O(5) atom. The Cu(1)-O(2) bond length is 1.94 Å. The Cu(1)-O(3) bond length is 1.96 Å. The Cu(1)-O(4) bond length is 2.02 Å. The Cu(1)-O(5) bond length is 2.01 Å. In the second Cu site, Cu(2) 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(2)-O(1) bond length is 2.01 Å. The Cu(2)-O(2) bond length is 2.02 Å. The Cu(2)-O(3) bond length is 1.96 Å. The Cu(2)-O(4) bond length is 1.94 Å. There are five inequivalent O sites. In the first O site, O(5) is bonded to one Y(2), two equivalent Y(1), and one Cu(1) atom to form OY3Cu tetrahedra that share corners with two equivalent O(5)Y3Cu tetrahedra, corners with four equivalent O(1)Y3Cu tetrahedra, corners with three equivalent O(2)Y2Cu2 trigonal pyramids, corners with three equivalent O(4)Y2Cu2 trigonal pyramids, and  an edgeedge with one O(2)Y2Cu2 trigonal pyramid. In the second O site, O(1) is bonded to one Y(1), two equivalent Y(2), and one Cu(2) atom to form OY3Cu tetrahedra that share corners with two equivalent O(1)Y3Cu tetrahedra, corners with four equivalent O(5)Y3Cu tetrahedra, corners with three equivalent O(2)Y2Cu2 trigonal pyramids, corners with three equivalent O(4)Y2Cu2 trigonal pyramids, and  an edgeedge with one O(4)Y2Cu2 trigonal pyramid. In the third O site, O(2) is bonded to two equivalent Y(1), one Cu(1), and one Cu(2) atom to form distorted OY2Cu2 trigonal pyramids that share corners with three equivalent O(1)Y3Cu tetrahedra, corners with three equivalent O(5)Y3Cu tetrahedra, corners with two equivalent O(2)Y2Cu2 trigonal pyramids,  an edgeedge with one O(5)Y3Cu tetrahedra, and  an edgeedge with one O(4)Y2Cu2 trigonal pyramid. In the fourth O site, O(3) is bonded in a distorted see-saw-like geometry to one Y(1), one Y(2), one Cu(1), and one Cu(2) atom. In the fifth O site, O(4) is bonded to two equivalent Y(2), one Cu(1), and one Cu(2) atom to form OY2Cu2 trigonal pyramids that share corners with three equivalent O(1)Y3Cu tetrahedra, corners with three equivalent O(5)Y3Cu tetrahedra, corners with two equivalent O(4)Y2Cu2 trigonal pyramids,  an edgeedge with one O(1)Y3Cu tetrahedra, and  an edgeedge with one O(2)Y2Cu2 trigonal pyramid.