Sr4Mg(Fe2O5)2 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(2), one O(3), one O(4), one O(7), one O(9), and two equivalent O(5) atoms. In the second Sr site, Sr(2) is bonded in a 7-coordinate geometry to one O(1), one O(10), one O(2), one O(3), one O(4), one O(6), and one O(8) atom. In the third Sr site, Sr(3) is bonded in a 7-coordinate geometry to one O(10), one O(2), one O(3), one O(4), one O(5), and two equivalent O(7) atoms. In the fourth Sr site, Sr(4) is bonded in a 8-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(6), one O(9), and two equivalent O(8) atoms. Mg(1) is bonded to one O(1), one O(10), one O(6), one O(8), and one O(9) atom to form distorted MgO5 trigonal bipyramids that share  a cornercorner with one Fe(4)O4 tetrahedra,  a cornercorner with one Fe(1)O5 trigonal bipyramid,  an edgeedge with one Fe(2)O6 octahedra, and  an edgeedge with one Fe(4)O4 tetrahedra. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(2), one O(3), one O(4), and one O(5) atom to form FeO5 trigonal bipyramids that share corners with four equivalent Fe(2)O6 octahedra and  a cornercorner with one Mg(1)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 2-53°. In the second Fe site, Fe(2) is bonded to one O(1), one O(2), one O(3), one O(4), one O(7), and one O(8) atom to form distorted FeO6 octahedra that share  a cornercorner with one Fe(4)O4 tetrahedra, corners with four equivalent Fe(1)O5 trigonal bipyramids, and  an edgeedge with one Mg(1)O5 trigonal bipyramid. In the third Fe site, Fe(3) is bonded in a 4-coordinate geometry to one O(10), one O(5), one O(8), and one O(9) atom. In the fourth Fe site, Fe(4) is bonded to one O(10), one O(6), one O(7), and one O(9) atom to form FeO4 tetrahedra that share  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one Mg(1)O5 trigonal bipyramid, and  an edgeedge with one Mg(1)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 32°. There are ten inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Sr(2), one Sr(4), one Mg(1), one Fe(1), and one Fe(2) atom. In the second O site, O(2) is bonded to one Sr(1), one Sr(2), one Sr(3), one Sr(4), one Fe(1), and one Fe(2) atom to form a mixture of corner, face, and edge-sharing OSr4Fe2 octahedra. The corner-sharing octahedral tilt angles are 9°. In the third O site, O(3) is bonded to one Sr(1), one Sr(2), one Sr(3), one Sr(4), one Fe(1), and one Fe(2) atom to form a mixture of corner, face, and edge-sharing OSr4Fe2 octahedra. The corner-sharing octahedral tilt angles are 9°. In the fourth O site, O(4) is bonded to one Sr(1), one Sr(2), one Sr(3), one Sr(4), one Fe(1), and one Fe(2) atom to form face-sharing OSr4Fe2 octahedra. In the fifth O site, O(5) is bonded in a 2-coordinate geometry to one Sr(3), two equivalent Sr(1), one Fe(1), and one Fe(3) atom. In the sixth O site, O(6) is bonded in a distorted see-saw-like geometry to one Sr(2), one Sr(4), one Mg(1), and one Fe(4) atom. In the seventh O site, O(7) is bonded in a 5-coordinate geometry to one Sr(1), two equivalent Sr(3), one Fe(2), and one Fe(4) atom. In the eighth O site, O(8) is bonded in a 6-coordinate geometry to one Sr(2), two equivalent Sr(4), one Mg(1), one Fe(2), and one Fe(3) atom. In the ninth O site, O(9) is bonded in a 5-coordinate geometry to one Sr(1), one Sr(4), one Mg(1), one Fe(3), and one Fe(4) atom. In the tenth O site, O(10) is bonded in a 5-coordinate geometry to one Sr(2), one Sr(3), one Mg(1), one Fe(3), and one Fe(4) atom.
Sr4Mg(Fe2O5)2 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(2), one O(3), one O(4), one O(7), one O(9), and two equivalent O(5) atoms. The Sr(1)-O(2) bond length is 2.67 Å. The Sr(1)-O(3) bond length is 2.61 Å. The Sr(1)-O(4) bond length is 2.69 Å. The Sr(1)-O(7) bond length is 2.58 Å. The Sr(1)-O(9) bond length is 2.60 Å. There is one shorter (2.74 Å) and one longer (2.99 Å) Sr(1)-O(5) bond length. In the second Sr site, Sr(2) is bonded in a 7-coordinate geometry to one O(1), one O(10), one O(2), one O(3), one O(4), one O(6), and one O(8) atom. The Sr(2)-O(1) bond length is 2.59 Å. The Sr(2)-O(10) bond length is 2.70 Å. The Sr(2)-O(2) bond length is 2.58 Å. The Sr(2)-O(3) bond length is 2.53 Å. The Sr(2)-O(4) bond length is 2.42 Å. The Sr(2)-O(6) bond length is 2.68 Å. The Sr(2)-O(8) bond length is 2.46 Å. In the third Sr site, Sr(3) is bonded in a 7-coordinate geometry to one O(10), one O(2), one O(3), one O(4), one O(5), and two equivalent O(7) atoms. The Sr(3)-O(10) bond length is 2.57 Å. The Sr(3)-O(2) bond length is 2.59 Å. The Sr(3)-O(3) bond length is 2.56 Å. The Sr(3)-O(4) bond length is 2.59 Å. The Sr(3)-O(5) bond length is 2.67 Å. There is one shorter (2.72 Å) and one longer (3.06 Å) Sr(3)-O(7) bond length. In the fourth Sr site, Sr(4) is bonded in a 8-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(6), one O(9), and two equivalent O(8) atoms. The Sr(4)-O(1) bond length is 2.91 Å. The Sr(4)-O(2) bond length is 2.67 Å. The Sr(4)-O(3) bond length is 2.69 Å. The Sr(4)-O(4) bond length is 2.54 Å. The Sr(4)-O(6) bond length is 2.55 Å. The Sr(4)-O(9) bond length is 2.63 Å. There is one shorter (2.76 Å) and one longer (3.05 Å) Sr(4)-O(8) bond length. Mg(1) is bonded to one O(1), one O(10), one O(6), one O(8), and one O(9) atom to form distorted MgO5 trigonal bipyramids that share  a cornercorner with one Fe(4)O4 tetrahedra,  a cornercorner with one Fe(1)O5 trigonal bipyramid,  an edgeedge with one Fe(2)O6 octahedra, and  an edgeedge with one Fe(4)O4 tetrahedra. The Mg(1)-O(1) bond length is 2.01 Å. The Mg(1)-O(10) bond length is 2.03 Å. The Mg(1)-O(6) bond length is 2.07 Å. The Mg(1)-O(8) bond length is 2.28 Å. The Mg(1)-O(9) bond length is 2.04 Å. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(2), one O(3), one O(4), and one O(5) atom to form FeO5 trigonal bipyramids that share corners with four equivalent Fe(2)O6 octahedra and  a cornercorner with one Mg(1)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 2-53°. The Fe(1)-O(1) bond length is 1.97 Å. The Fe(1)-O(2) bond length is 2.04 Å. The Fe(1)-O(3) bond length is 2.04 Å. The Fe(1)-O(4) bond length is 2.00 Å. The Fe(1)-O(5) bond length is 1.95 Å. In the second Fe site, Fe(2) is bonded to one O(1), one O(2), one O(3), one O(4), one O(7), and one O(8) atom to form distorted FeO6 octahedra that share  a cornercorner with one Fe(4)O4 tetrahedra, corners with four equivalent Fe(1)O5 trigonal bipyramids, and  an edgeedge with one Mg(1)O5 trigonal bipyramid. The Fe(2)-O(1) bond length is 2.04 Å. The Fe(2)-O(2) bond length is 2.25 Å. The Fe(2)-O(3) bond length is 2.33 Å. The Fe(2)-O(4) bond length is 2.12 Å. The Fe(2)-O(7) bond length is 2.21 Å. The Fe(2)-O(8) bond length is 2.43 Å. In the third Fe site, Fe(3) is bonded in a 4-coordinate geometry to one O(10), one O(5), one O(8), and one O(9) atom. The Fe(3)-O(10) bond length is 2.53 Å. The Fe(3)-O(5) bond length is 1.89 Å. The Fe(3)-O(8) bond length is 1.89 Å. The Fe(3)-O(9) bond length is 2.29 Å. In the fourth Fe site, Fe(4) is bonded to one O(10), one O(6), one O(7), and one O(9) atom to form FeO4 tetrahedra that share  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one Mg(1)O5 trigonal bipyramid, and  an edgeedge with one Mg(1)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 32°. The Fe(4)-O(10) bond length is 1.94 Å. The Fe(4)-O(6) bond length is 1.91 Å. The Fe(4)-O(7) bond length is 1.87 Å. The Fe(4)-O(9) bond length is 1.98 Å. There are ten inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Sr(2), one Sr(4), one Mg(1), one Fe(1), and one Fe(2) atom. In the second O site, O(2) is bonded to one Sr(1), one Sr(2), one Sr(3), one Sr(4), one Fe(1), and one Fe(2) atom to form a mixture of corner, face, and edge-sharing OSr4Fe2 octahedra. The corner-sharing octahedral tilt angles are 9°. In the third O site, O(3) is bonded to one Sr(1), one Sr(2), one Sr(3), one Sr(4), one Fe(1), and one Fe(2) atom to form a mixture of corner, face, and edge-sharing OSr4Fe2 octahedra. The corner-sharing octahedral tilt angles are 9°. In the fourth O site, O(4) is bonded to one Sr(1), one Sr(2), one Sr(3), one Sr(4), one Fe(1), and one Fe(2) atom to form face-sharing OSr4Fe2 octahedra. In the fifth O site, O(5) is bonded in a 2-coordinate geometry to one Sr(3), two equivalent Sr(1), one Fe(1), and one Fe(3) atom. In the sixth O site, O(6) is bonded in a distorted see-saw-like geometry to one Sr(2), one Sr(4), one Mg(1), and one Fe(4) atom. In the seventh O site, O(7) is bonded in a 5-coordinate geometry to one Sr(1), two equivalent Sr(3), one Fe(2), and one Fe(4) atom. In the eighth O site, O(8) is bonded in a 6-coordinate geometry to one Sr(2), two equivalent Sr(4), one Mg(1), one Fe(2), and one Fe(3) atom. In the ninth O site, O(9) is bonded in a 5-coordinate geometry to one Sr(1), one Sr(4), one Mg(1), one Fe(3), and one Fe(4) atom. In the tenth O site, O(10) is bonded in a 5-coordinate geometry to one Sr(2), one Sr(3), one Mg(1), one Fe(3), and one Fe(4) atom.