Sr2Cu2AlSnO7 crystallizes in the triclinic P1 space group. There are four inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 7-coordinate geometry to one O(1), one O(3), one O(7), two equivalent O(11), and two equivalent O(13) atoms. In the second Sr site, Sr(2) is bonded in a 7-coordinate geometry to one O(2), one O(4), one O(8), two equivalent O(12), and two equivalent O(14) atoms. In the third Sr site, Sr(3) is bonded in a 7-coordinate geometry to one O(2), one O(5), one O(9), two equivalent O(11), and two equivalent O(13) atoms. In the fourth Sr site, Sr(4) is bonded in a 7-coordinate geometry to one O(1), one O(10), one O(6), two equivalent O(12), and two equivalent O(14) atoms. There are four inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to one O(13), one O(3), one O(5), one O(7), and one O(9) atom to form distorted CuO5 square pyramids that share corners with two equivalent Al(1)O4 tetrahedra and corners with two equivalent Al(2)O4 tetrahedra. In the second Cu site, Cu(2) is bonded in a rectangular see-saw-like geometry to one O(10), one O(14), one O(4), one O(6), and one O(8) atom. In the third Cu site, Cu(3) is bonded in a rectangular see-saw-like geometry to one O(11), one O(3), one O(5), one O(7), and one O(9) atom. In the fourth Cu site, Cu(4) is bonded to one O(10), one O(12), one O(4), one O(6), and one O(8) atom to form distorted CuO5 square pyramids that share corners with two equivalent Al(1)O4 tetrahedra and corners with two equivalent Al(2)O4 tetrahedra. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(10), one O(5), one O(6), and one O(9) atom to form distorted AlO4 tetrahedra that share corners with two equivalent Cu(1)O5 square pyramids and corners with two equivalent Cu(4)O5 square pyramids. In the second Al site, Al(2) is bonded to one O(3), one O(4), one O(7), and one O(8) atom to form distorted AlO4 tetrahedra that share corners with two equivalent Cu(1)O5 square pyramids and corners with two equivalent Cu(4)O5 square pyramids. There are two inequivalent Sn sites. In the first Sn site, Sn(1) is bonded in a trigonal pyramidal geometry to one O(1), one O(11), one O(14), and one O(2) atom. In the second Sn site, Sn(2) is bonded in a rectangular see-saw-like geometry to one O(1), one O(12), one O(13), and one O(2) atom. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted see-saw-like geometry to one Sr(1), one Sr(4), one Sn(1), and one Sn(2) atom. In the second O site, O(2) is bonded to one Sr(2), one Sr(3), one Sn(1), and one Sn(2) atom to form a mixture of distorted corner and edge-sharing OSr2Sn2 tetrahedra. The corner-sharing octahedral tilt angles are 88°. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Sr(1), one Cu(1), one Cu(3), and one Al(2) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Sr(2), one Cu(2), one Cu(4), and one Al(2) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Sr(3), one Cu(1), one Cu(3), and one Al(1) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Sr(4), one Cu(2), one Cu(4), and one Al(1) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one Sr(1), one Cu(1), one Cu(3), and one Al(2) atom. In the eighth O site, O(8) is bonded in a 4-coordinate geometry to one Sr(2), one Cu(2), one Cu(4), and one Al(2) atom. In the ninth O site, O(9) is bonded in a 4-coordinate geometry to one Sr(3), one Cu(1), one Cu(3), and one Al(1) atom. In the tenth O site, O(10) is bonded in a 4-coordinate geometry to one Sr(4), one Cu(2), one Cu(4), and one Al(1) atom. In the eleventh O site, O(11) is bonded in a 6-coordinate geometry to two equivalent Sr(1), two equivalent Sr(3), one Cu(3), and one Sn(1) atom. In the twelfth O site, O(12) is bonded to two equivalent Sr(2), two equivalent Sr(4), one Cu(4), and one Sn(2) atom to form distorted OSr4CuSn octahedra that share  a cornercorner with one O(13)Sr4CuSn octahedra, corners with four equivalent O(12)Sr4CuSn octahedra,  a cornercorner with one O(2)Sr2Sn2 tetrahedra, and  an edgeedge with one O(2)Sr2Sn2 tetrahedra. The corner-sharing octahedral tilt angles range from 11-22°. In the thirteenth O site, O(13) is bonded to two equivalent Sr(1), two equivalent Sr(3), one Cu(1), and one Sn(2) atom to form distorted OSr4CuSn octahedra that share  a cornercorner with one O(12)Sr4CuSn octahedra, corners with four equivalent O(13)Sr4CuSn octahedra,  a cornercorner with one O(2)Sr2Sn2 tetrahedra, and  an edgeedge with one O(2)Sr2Sn2 tetrahedra. The corner-sharing octahedral tilt angles range from 11-22°. In the fourteenth O site, O(14) is bonded in a 6-coordinate geometry to two equivalent Sr(2), two equivalent Sr(4), one Cu(2), and one Sn(1) atom.
Sr2Cu2AlSnO7 crystallizes in the triclinic P1 space group. There are four inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 7-coordinate geometry to one O(1), one O(3), one O(7), two equivalent O(11), and two equivalent O(13) atoms. The Sr(1)-O(1) bond length is 2.71 Å. The Sr(1)-O(3) bond length is 2.48 Å. The Sr(1)-O(7) bond length is 2.50 Å. There is one shorter (2.63 Å) and one longer (2.93 Å) Sr(1)-O(11) bond length. There is one shorter (2.72 Å) and one longer (2.74 Å) Sr(1)-O(13) bond length. In the second Sr site, Sr(2) is bonded in a 7-coordinate geometry to one O(2), one O(4), one O(8), two equivalent O(12), and two equivalent O(14) atoms. The Sr(2)-O(2) bond length is 2.71 Å. The Sr(2)-O(4) bond length is 2.51 Å. The Sr(2)-O(8) bond length is 2.49 Å. There is one shorter (2.67 Å) and one longer (2.84 Å) Sr(2)-O(12) bond length. There is one shorter (2.71 Å) and one longer (2.81 Å) Sr(2)-O(14) bond length. In the third Sr site, Sr(3) is bonded in a 7-coordinate geometry to one O(2), one O(5), one O(9), two equivalent O(11), and two equivalent O(13) atoms. The Sr(3)-O(2) bond length is 2.71 Å. The Sr(3)-O(5) bond length is 2.49 Å. The Sr(3)-O(9) bond length is 2.49 Å. There is one shorter (2.70 Å) and one longer (2.83 Å) Sr(3)-O(11) bond length. There is one shorter (2.67 Å) and one longer (2.83 Å) Sr(3)-O(13) bond length. In the fourth Sr site, Sr(4) is bonded in a 7-coordinate geometry to one O(1), one O(10), one O(6), two equivalent O(12), and two equivalent O(14) atoms. The Sr(4)-O(1) bond length is 2.71 Å. The Sr(4)-O(10) bond length is 2.49 Å. The Sr(4)-O(6) bond length is 2.50 Å. There is one shorter (2.72 Å) and one longer (2.74 Å) Sr(4)-O(12) bond length. There is one shorter (2.61 Å) and one longer (2.96 Å) Sr(4)-O(14) bond length. There are four inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to one O(13), one O(3), one O(5), one O(7), and one O(9) atom to form distorted CuO5 square pyramids that share corners with two equivalent Al(1)O4 tetrahedra and corners with two equivalent Al(2)O4 tetrahedra. The Cu(1)-O(13) bond length is 2.50 Å. The Cu(1)-O(3) bond length is 1.99 Å. The Cu(1)-O(5) bond length is 1.99 Å. The Cu(1)-O(7) bond length is 2.00 Å. The Cu(1)-O(9) 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(10), one O(14), one O(4), one O(6), and one O(8) atom. The Cu(2)-O(10) bond length is 1.98 Å. The Cu(2)-O(14) bond length is 2.73 Å. The Cu(2)-O(4) bond length is 1.97 Å. The Cu(2)-O(6) bond length is 2.00 Å. The Cu(2)-O(8) bond length is 1.97 Å. In the third Cu site, Cu(3) is bonded in a rectangular see-saw-like geometry to one O(11), one O(3), one O(5), one O(7), and one O(9) atom. The Cu(3)-O(11) bond length is 2.71 Å. The Cu(3)-O(3) bond length is 1.98 Å. The Cu(3)-O(5) bond length is 1.97 Å. The Cu(3)-O(7) bond length is 1.99 Å. The Cu(3)-O(9) bond length is 1.97 Å. In the fourth Cu site, Cu(4) is bonded to one O(10), one O(12), one O(4), one O(6), and one O(8) atom to form distorted CuO5 square pyramids that share corners with two equivalent Al(1)O4 tetrahedra and corners with two equivalent Al(2)O4 tetrahedra. The Cu(4)-O(10) bond length is 1.99 Å. The Cu(4)-O(12) bond length is 2.52 Å. The Cu(4)-O(4) bond length is 2.01 Å. The Cu(4)-O(6) bond length is 2.01 Å. The Cu(4)-O(8) bond length is 1.99 Å. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(10), one O(5), one O(6), and one O(9) atom to form distorted AlO4 tetrahedra that share corners with two equivalent Cu(1)O5 square pyramids and corners with two equivalent Cu(4)O5 square pyramids. The Al(1)-O(10) bond length is 1.84 Å. The Al(1)-O(5) bond length is 1.83 Å. The Al(1)-O(6) bond length is 1.84 Å. The Al(1)-O(9) bond length is 1.84 Å. In the second Al site, Al(2) is bonded to one O(3), one O(4), one O(7), and one O(8) atom to form distorted AlO4 tetrahedra that share corners with two equivalent Cu(1)O5 square pyramids and corners with two equivalent Cu(4)O5 square pyramids. The Al(2)-O(3) bond length is 1.83 Å. The Al(2)-O(4) bond length is 1.84 Å. The Al(2)-O(7) bond length is 1.84 Å. The Al(2)-O(8) bond length is 1.84 Å. There are two inequivalent Sn sites. In the first Sn site, Sn(1) is bonded in a trigonal pyramidal geometry to one O(1), one O(11), one O(14), and one O(2) atom. The Sn(1)-O(1) bond length is 2.07 Å. The Sn(1)-O(11) bond length is 2.02 Å. The Sn(1)-O(14) bond length is 2.02 Å. The Sn(1)-O(2) bond length is 2.07 Å. In the second Sn site, Sn(2) is bonded in a rectangular see-saw-like geometry to one O(1), one O(12), one O(13), and one O(2) atom. The Sn(2)-O(1) bond length is 2.12 Å. The Sn(2)-O(12) bond length is 2.11 Å. The Sn(2)-O(13) bond length is 2.11 Å. The Sn(2)-O(2) bond length is 2.12 Å. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted see-saw-like geometry to one Sr(1), one Sr(4), one Sn(1), and one Sn(2) atom. In the second O site, O(2) is bonded to one Sr(2), one Sr(3), one Sn(1), and one Sn(2) atom to form a mixture of distorted corner and edge-sharing OSr2Sn2 tetrahedra. The corner-sharing octahedral tilt angles are 88°. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Sr(1), one Cu(1), one Cu(3), and one Al(2) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Sr(2), one Cu(2), one Cu(4), and one Al(2) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Sr(3), one Cu(1), one Cu(3), and one Al(1) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Sr(4), one Cu(2), one Cu(4), and one Al(1) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one Sr(1), one Cu(1), one Cu(3), and one Al(2) atom. In the eighth O site, O(8) is bonded in a 4-coordinate geometry to one Sr(2), one Cu(2), one Cu(4), and one Al(2) atom. In the ninth O site, O(9) is bonded in a 4-coordinate geometry to one Sr(3), one Cu(1), one Cu(3), and one Al(1) atom. In the tenth O site, O(10) is bonded in a 4-coordinate geometry to one Sr(4), one Cu(2), one Cu(4), and one Al(1) atom. In the eleventh O site, O(11) is bonded in a 6-coordinate geometry to two equivalent Sr(1), two equivalent Sr(3), one Cu(3), and one Sn(1) atom. In the twelfth O site, O(12) is bonded to two equivalent Sr(2), two equivalent Sr(4), one Cu(4), and one Sn(2) atom to form distorted OSr4CuSn octahedra that share  a cornercorner with one O(13)Sr4CuSn octahedra, corners with four equivalent O(12)Sr4CuSn octahedra,  a cornercorner with one O(2)Sr2Sn2 tetrahedra, and  an edgeedge with one O(2)Sr2Sn2 tetrahedra. The corner-sharing octahedral tilt angles range from 11-22°. In the thirteenth O site, O(13) is bonded to two equivalent Sr(1), two equivalent Sr(3), one Cu(1), and one Sn(2) atom to form distorted OSr4CuSn octahedra that share  a cornercorner with one O(12)Sr4CuSn octahedra, corners with four equivalent O(13)Sr4CuSn octahedra,  a cornercorner with one O(2)Sr2Sn2 tetrahedra, and  an edgeedge with one O(2)Sr2Sn2 tetrahedra. The corner-sharing octahedral tilt angles range from 11-22°. In the fourteenth O site, O(14) is bonded in a 6-coordinate geometry to two equivalent Sr(2), two equivalent Sr(4), one Cu(2), and one Sn(1) atom.