SrCuAs2O7 crystallizes in the monoclinic P2_1/c space group. Sr(1) is bonded in a 9-coordinate geometry to one O(4), one O(5), one O(6), two equivalent O(1), two equivalent O(2), and two equivalent O(7) atoms. Cu(1) is bonded to one O(2), one O(4), one O(5), one O(6), and one O(7) atom to form distorted CuO5 square pyramids that share corners with two equivalent As(2)O4 tetrahedra and corners with three equivalent As(1)O4 tetrahedra. There are two inequivalent As sites. In the first As site, As(1) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form AsO4 tetrahedra that share corners with three equivalent Cu(1)O5 square pyramids and  a cornercorner with one As(2)O4 tetrahedra. In the second As site, As(2) is bonded to one O(1), one O(3), one O(6), and one O(7) atom to form AsO4 tetrahedra that share corners with two equivalent Cu(1)O5 square pyramids and  a cornercorner with one As(1)O4 tetrahedra. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to two equivalent Sr(1) and one As(2) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to two equivalent Sr(1), one Cu(1), and one As(1) atom. In the third O site, O(3) is bonded in a bent 120 degrees geometry to one As(1) and one As(2) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Sr(1), one Cu(1), and one As(1) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Sr(1), one Cu(1), and one As(1) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Sr(1), one Cu(1), and one As(2) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to two equivalent Sr(1), one Cu(1), and one As(2) atom.
SrCuAs2O7 crystallizes in the monoclinic P2_1/c space group. Sr(1) is bonded in a 9-coordinate geometry to one O(4), one O(5), one O(6), two equivalent O(1), two equivalent O(2), and two equivalent O(7) atoms. The Sr(1)-O(4) bond length is 2.81 Å. The Sr(1)-O(5) bond length is 2.62 Å. The Sr(1)-O(6) bond length is 2.70 Å. There is one shorter (2.54 Å) and one longer (2.61 Å) Sr(1)-O(1) bond length. There is one shorter (2.74 Å) and one longer (3.01 Å) Sr(1)-O(2) bond length. There is one shorter (2.68 Å) and one longer (2.96 Å) Sr(1)-O(7) bond length. Cu(1) is bonded to one O(2), one O(4), one O(5), one O(6), and one O(7) atom to form distorted CuO5 square pyramids that share corners with two equivalent As(2)O4 tetrahedra and corners with three equivalent As(1)O4 tetrahedra. The Cu(1)-O(2) bond length is 2.38 Å. The Cu(1)-O(4) bond length is 2.01 Å. The Cu(1)-O(5) bond length is 1.98 Å. The Cu(1)-O(6) bond length is 1.94 Å. The Cu(1)-O(7) bond length is 2.05 Å. There are two inequivalent As sites. In the first As site, As(1) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form AsO4 tetrahedra that share corners with three equivalent Cu(1)O5 square pyramids and  a cornercorner with one As(2)O4 tetrahedra. The As(1)-O(2) bond length is 1.69 Å. The As(1)-O(3) bond length is 1.80 Å. The As(1)-O(4) bond length is 1.74 Å. The As(1)-O(5) bond length is 1.73 Å. In the second As site, As(2) is bonded to one O(1), one O(3), one O(6), and one O(7) atom to form AsO4 tetrahedra that share corners with two equivalent Cu(1)O5 square pyramids and  a cornercorner with one As(1)O4 tetrahedra. The As(2)-O(1) bond length is 1.69 Å. The As(2)-O(3) bond length is 1.78 Å. The As(2)-O(6) bond length is 1.71 Å. The As(2)-O(7) bond length is 1.73 Å. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to two equivalent Sr(1) and one As(2) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to two equivalent Sr(1), one Cu(1), and one As(1) atom. In the third O site, O(3) is bonded in a bent 120 degrees geometry to one As(1) and one As(2) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Sr(1), one Cu(1), and one As(1) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Sr(1), one Cu(1), and one As(1) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Sr(1), one Cu(1), and one As(2) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to two equivalent Sr(1), one Cu(1), and one As(2) atom.