Sr3Ir2O7 crystallizes in the monoclinic C2/m space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 6-coordinate geometry to one O(1), one O(2), and four equivalent O(3) atoms. In the second Sr site, Sr(2) is bonded in a distorted octahedral geometry to two equivalent O(2) and four equivalent O(3) atoms. Ir(1) is bonded in a rectangular see-saw-like geometry to one O(1), one O(2), and two equivalent O(3) atoms. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted linear geometry to two equivalent Sr(1) and two equivalent Ir(1) atoms. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Sr(1), one Sr(2), and one Ir(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Sr(2), two equivalent Sr(1), and one Ir(1) atom.
Sr3Ir2O7 crystallizes in the monoclinic C2/m space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 6-coordinate geometry to one O(1), one O(2), and four equivalent O(3) atoms. The Sr(1)-O(1) bond length is 2.98 Å. The Sr(1)-O(2) bond length is 2.48 Å. There are two shorter (2.47 Å) and two longer (2.83 Å) Sr(1)-O(3) bond lengths. In the second Sr site, Sr(2) is bonded in a distorted octahedral geometry to two equivalent O(2) and four equivalent O(3) atoms. Both Sr(2)-O(2) bond lengths are 2.62 Å. All Sr(2)-O(3) bond lengths are 2.46 Å. Ir(1) is bonded in a rectangular see-saw-like geometry to one O(1), one O(2), and two equivalent O(3) atoms. The Ir(1)-O(1) bond length is 1.90 Å. The Ir(1)-O(2) bond length is 1.89 Å. Both Ir(1)-O(3) bond lengths are 1.92 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted linear geometry to two equivalent Sr(1) and two equivalent Ir(1) atoms. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Sr(1), one Sr(2), and one Ir(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Sr(2), two equivalent Sr(1), and one Ir(1) atom.