Sr3Ir2O7 crystallizes in the orthorhombic Ccce space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 8-coordinate geometry to four equivalent O(2) and four equivalent O(3) atoms. In the second Sr site, Sr(2) is bonded in a 7-coordinate geometry to two equivalent O(2) and five equivalent O(1) atoms. Ir(1) is bonded to one O(1), one O(3), and four equivalent O(2) atoms to form corner-sharing IrO6 octahedra. The corner-sharing octahedral tilt angles range from 0-27°. There are three inequivalent O sites. In the first O site, O(1) is bonded to five equivalent Sr(2) and one Ir(1) atom to form OSr5Ir octahedra that share  a cornercorner with one O(3)Sr4Ir2 octahedra, corners with four equivalent O(1)Sr5Ir octahedra, and edges with eight equivalent O(1)Sr5Ir octahedra. The corner-sharing octahedral tilt angles range from 0-6°. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Sr(1), one Sr(2), and two equivalent Ir(1) atoms. In the third O site, O(3) is bonded to four equivalent Sr(1) and two equivalent Ir(1) atoms to form OSr4Ir2 octahedra that share corners with two equivalent O(1)Sr5Ir octahedra, corners with four equivalent O(3)Sr4Ir2 octahedra, and edges with four equivalent O(3)Sr4Ir2 octahedra. The corner-sharing octahedra are not tilted.
Sr3Ir2O7 crystallizes in the orthorhombic Ccce space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 8-coordinate geometry to four equivalent O(2) and four equivalent O(3) atoms. All Sr(1)-O(2) bond lengths are 2.51 Å. All Sr(1)-O(3) bond lengths are 2.77 Å. In the second Sr site, Sr(2) is bonded in a 7-coordinate geometry to two equivalent O(2) and five equivalent O(1) atoms. Both Sr(2)-O(2) bond lengths are 2.42 Å. There is one shorter (2.49 Å) and four longer (2.77 Å) Sr(2)-O(1) bond lengths. Ir(1) is bonded to one O(1), one O(3), and four equivalent O(2) atoms to form corner-sharing IrO6 octahedra. The corner-sharing octahedral tilt angles range from 0-27°. The Ir(1)-O(1) bond length is 2.03 Å. The Ir(1)-O(3) bond length is 2.04 Å. All Ir(1)-O(2) bond lengths are 2.01 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded to five equivalent Sr(2) and one Ir(1) atom to form OSr5Ir octahedra that share  a cornercorner with one O(3)Sr4Ir2 octahedra, corners with four equivalent O(1)Sr5Ir octahedra, and edges with eight equivalent O(1)Sr5Ir octahedra. The corner-sharing octahedral tilt angles range from 0-6°. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Sr(1), one Sr(2), and two equivalent Ir(1) atoms. In the third O site, O(3) is bonded to four equivalent Sr(1) and two equivalent Ir(1) atoms to form OSr4Ir2 octahedra that share corners with two equivalent O(1)Sr5Ir octahedra, corners with four equivalent O(3)Sr4Ir2 octahedra, and edges with four equivalent O(3)Sr4Ir2 octahedra. The corner-sharing octahedra are not tilted.