Sr2YCr2TlO7 crystallizes in the tetragonal P4/mmm space group. Sr(1) is bonded to one O(3) and four equivalent O(2) atoms to form distorted SrO5 square pyramids that share corners with four equivalent Cr(1)O5 square pyramids, corners with five equivalent Sr(1)O5 square pyramids, edges with four equivalent Tl(1)O6 octahedra, and edges with four equivalent Sr(1)O5 square pyramids. Y(1) is bonded in a body-centered cubic geometry to eight equivalent O(1) atoms. Cr(1) is bonded to one O(2) and four equivalent O(1) atoms to form distorted CrO5 square pyramids that share  a cornercorner with one Tl(1)O6 octahedra, corners with four equivalent Sr(1)O5 square pyramids, and corners with four equivalent Cr(1)O5 square pyramids. The corner-sharing octahedra are not tilted. Tl(1) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form TlO6 octahedra that share corners with four equivalent Tl(1)O6 octahedra, corners with two equivalent Cr(1)O5 square pyramids, edges with four equivalent Tl(1)O6 octahedra, and edges with eight equivalent Sr(1)O5 square pyramids. The corner-sharing octahedra are not tilted. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to two equivalent Y(1) and two equivalent Cr(1) atoms. In the second O site, O(2) is bonded to four equivalent Sr(1), one Cr(1), and one Tl(1) atom to form distorted OSr4TlCr octahedra that share corners with five equivalent O(2)Sr4TlCr octahedra, edges with four equivalent O(3)Sr2Tl4 octahedra, and edges with four equivalent O(2)Sr4TlCr octahedra. The corner-sharing octahedral tilt angles range from 0-8°. In the third O site, O(3) is bonded to two equivalent Sr(1) and four equivalent Tl(1) atoms to form OSr2Tl4 octahedra that share corners with four equivalent O(3)Sr2Tl4 octahedra, edges with four equivalent O(3)Sr2Tl4 octahedra, and edges with eight equivalent O(2)Sr4TlCr octahedra. The corner-sharing octahedra are not tilted.
Sr2YCr2TlO7 crystallizes in the tetragonal P4/mmm space group. Sr(1) is bonded to one O(3) and four equivalent O(2) atoms to form distorted SrO5 square pyramids that share corners with four equivalent Cr(1)O5 square pyramids, corners with five equivalent Sr(1)O5 square pyramids, edges with four equivalent Tl(1)O6 octahedra, and edges with four equivalent Sr(1)O5 square pyramids. The Sr(1)-O(3) bond length is 2.44 Å. All Sr(1)-O(2) bond lengths are 2.75 Å. Y(1) is bonded in a body-centered cubic geometry to eight equivalent O(1) atoms. All Y(1)-O(1) bond lengths are 2.41 Å. Cr(1) is bonded to one O(2) and four equivalent O(1) atoms to form distorted CrO5 square pyramids that share  a cornercorner with one Tl(1)O6 octahedra, corners with four equivalent Sr(1)O5 square pyramids, and corners with four equivalent Cr(1)O5 square pyramids. The corner-sharing octahedra are not tilted. The Cr(1)-O(2) bond length is 1.92 Å. All Cr(1)-O(1) bond lengths are 1.99 Å. Tl(1) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form TlO6 octahedra that share corners with four equivalent Tl(1)O6 octahedra, corners with two equivalent Cr(1)O5 square pyramids, edges with four equivalent Tl(1)O6 octahedra, and edges with eight equivalent Sr(1)O5 square pyramids. The corner-sharing octahedra are not tilted. Both Tl(1)-O(2) bond lengths are 2.63 Å. All Tl(1)-O(3) bond lengths are 2.75 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to two equivalent Y(1) and two equivalent Cr(1) atoms. In the second O site, O(2) is bonded to four equivalent Sr(1), one Cr(1), and one Tl(1) atom to form distorted OSr4TlCr octahedra that share corners with five equivalent O(2)Sr4TlCr octahedra, edges with four equivalent O(3)Sr2Tl4 octahedra, and edges with four equivalent O(2)Sr4TlCr octahedra. The corner-sharing octahedral tilt angles range from 0-8°. In the third O site, O(3) is bonded to two equivalent Sr(1) and four equivalent Tl(1) atoms to form OSr2Tl4 octahedra that share corners with four equivalent O(3)Sr2Tl4 octahedra, edges with four equivalent O(3)Sr2Tl4 octahedra, and edges with eight equivalent O(2)Sr4TlCr octahedra. The corner-sharing octahedra are not tilted.