Sr3MgFe2O7 crystallizes in the monoclinic C2/m space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to one O(3), two equivalent O(1), and three equivalent O(2) atoms to form distorted edge-sharing SrO6 pentagonal pyramids. In the second Sr site, Sr(2) is bonded in a distorted square co-planar geometry to four equivalent O(1) atoms. Mg(1) is bonded in a square co-planar geometry to two equivalent O(3) and two equivalent O(4) atoms. Fe(1) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(4), and two equivalent O(3) atoms. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to two equivalent Sr(1), two equivalent Sr(2), and one Fe(1) atom. In the second O site, O(2) is bonded to three equivalent Sr(1) and one Fe(1) atom to form a mixture of distorted edge and corner-sharing OSr3Fe trigonal pyramids. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Sr(1), one Mg(1), and two equivalent Fe(1) atoms. In the fourth O site, O(4) is bonded in a square co-planar geometry to two equivalent Mg(1) and two equivalent Fe(1) atoms.
Sr3MgFe2O7 crystallizes in the monoclinic C2/m space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to one O(3), two equivalent O(1), and three equivalent O(2) atoms to form distorted edge-sharing SrO6 pentagonal pyramids. The Sr(1)-O(3) bond length is 2.47 Å. Both Sr(1)-O(1) bond lengths are 2.79 Å. There is one shorter (2.40 Å) and two longer (2.54 Å) Sr(1)-O(2) bond lengths. In the second Sr site, Sr(2) is bonded in a distorted square co-planar geometry to four equivalent O(1) atoms. All Sr(2)-O(1) bond lengths are 2.69 Å. Mg(1) is bonded in a square co-planar geometry to two equivalent O(3) and two equivalent O(4) atoms. Both Mg(1)-O(3) bond lengths are 1.91 Å. Both Mg(1)-O(4) bond lengths are 1.89 Å. Fe(1) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(4), and two equivalent O(3) atoms. The Fe(1)-O(1) bond length is 1.94 Å. The Fe(1)-O(2) bond length is 1.90 Å. The Fe(1)-O(4) bond length is 2.27 Å. Both Fe(1)-O(3) bond lengths are 2.02 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to two equivalent Sr(1), two equivalent Sr(2), and one Fe(1) atom. In the second O site, O(2) is bonded to three equivalent Sr(1) and one Fe(1) atom to form a mixture of distorted edge and corner-sharing OSr3Fe trigonal pyramids. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Sr(1), one Mg(1), and two equivalent Fe(1) atoms. In the fourth O site, O(4) is bonded in a square co-planar geometry to two equivalent Mg(1) and two equivalent Fe(1) atoms.