Sr4MgFe4O11 crystallizes in the triclinic P1 space group. There are four inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 11-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(5), one O(6), one O(7), one O(8), one O(9), and two equivalent O(10) atoms. In the second Sr site, Sr(2) is bonded in a 6-coordinate geometry to one O(1), one O(11), one O(2), one O(4), one O(6), one O(7), and one O(9) atom. In the third Sr site, Sr(3) is bonded in a 8-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(5), one O(6), one O(7), and one O(8) atom. In the fourth Sr site, Sr(4) is bonded in a 7-coordinate geometry to one O(10), one O(11), one O(2), one O(4), one O(5), one O(7), and two equivalent O(9) atoms. Mg(1) is bonded in a 5-coordinate geometry to one O(1), one O(11), one O(3), one O(6), and one O(8) atom. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(10), one O(2), one O(5), and one O(6) atom to form FeO5 square pyramids that share  a cornercorner with one Fe(2)O6 octahedra, corners with two equivalent Fe(3)O5 trigonal bipyramids, and corners with two equivalent Fe(4)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 30°. In the second Fe site, Fe(2) is bonded to one O(10), one O(11), one O(3), one O(4), one O(7), and one O(8) atom to form corner-sharing FeO6 octahedra. In the third Fe site, Fe(3) is bonded to one O(2), one O(4), one O(5), one O(7), and one O(9) atom to form distorted FeO5 trigonal bipyramids that share corners with two equivalent Fe(2)O6 octahedra, corners with two equivalent Fe(1)O5 square pyramids, and  a cornercorner with one Fe(4)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 26-27°. In the fourth Fe site, Fe(4) is bonded to one O(1), one O(3), one O(6), one O(8), and one O(9) atom to form distorted FeO5 trigonal bipyramids that share corners with two equivalent Fe(2)O6 octahedra, corners with two equivalent Fe(1)O5 square pyramids, and  a cornercorner with one Fe(3)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 36-37°. There are eleven inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to one Sr(1), one Sr(2), one Sr(3), one Mg(1), one Fe(1), and one Fe(4) atom. In the second O site, O(2) is bonded in a 6-coordinate geometry to one Sr(1), one Sr(2), one Sr(3), one Sr(4), one Fe(1), and one Fe(3) atom. In the third O site, O(3) is bonded in a distorted trigonal bipyramidal geometry to one Sr(1), one Sr(3), one Mg(1), one Fe(2), and one Fe(4) atom. In the fourth O site, O(4) is bonded in a 6-coordinate geometry to one Sr(1), one Sr(2), one Sr(3), one Sr(4), one Fe(2), and one Fe(3) atom. In the fifth O site, O(5) is bonded in a 5-coordinate geometry to one Sr(1), one Sr(3), one Sr(4), one Fe(1), and one Fe(3) atom. In the sixth O site, O(6) is bonded in a distorted T-shaped geometry to one Sr(1), one Sr(2), one Sr(3), one Mg(1), one Fe(1), and one Fe(4) atom. In the seventh O site, O(7) is bonded in a 5-coordinate geometry to one Sr(1), one Sr(2), one Sr(3), one Sr(4), one Fe(2), and one Fe(3) atom. In the eighth O site, O(8) is bonded in a 5-coordinate geometry to one Sr(1), one Sr(3), one Mg(1), one Fe(2), and one Fe(4) atom. In the ninth O site, O(9) is bonded in a 6-coordinate geometry to one Sr(1), one Sr(2), two equivalent Sr(4), 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(4), two equivalent Sr(1), one Fe(1), and one Fe(2) atom. In the eleventh O site, O(11) is bonded in a 4-coordinate geometry to one Sr(2), one Sr(4), one Mg(1), and one Fe(2) atom.
Sr4MgFe4O11 crystallizes in the triclinic P1 space group. There are four inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 11-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(5), one O(6), one O(7), one O(8), one O(9), and two equivalent O(10) atoms. The Sr(1)-O(1) bond length is 3.12 Å. The Sr(1)-O(2) bond length is 2.70 Å. The Sr(1)-O(3) bond length is 2.59 Å. The Sr(1)-O(4) bond length is 3.01 Å. The Sr(1)-O(5) bond length is 2.68 Å. The Sr(1)-O(6) bond length is 3.22 Å. The Sr(1)-O(7) bond length is 3.23 Å. The Sr(1)-O(8) bond length is 2.47 Å. The Sr(1)-O(9) bond length is 2.84 Å. There is one shorter (2.84 Å) and one longer (2.87 Å) Sr(1)-O(10) bond length. In the second Sr site, Sr(2) is bonded in a 6-coordinate geometry to one O(1), one O(11), one O(2), one O(4), one O(6), one O(7), and one O(9) atom. The Sr(2)-O(1) bond length is 2.73 Å. The Sr(2)-O(11) bond length is 2.61 Å. The Sr(2)-O(2) bond length is 3.13 Å. The Sr(2)-O(4) bond length is 2.71 Å. The Sr(2)-O(6) bond length is 2.97 Å. The Sr(2)-O(7) bond length is 2.63 Å. The Sr(2)-O(9) bond length is 2.65 Å. In the third Sr site, Sr(3) is bonded in a 8-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(5), one O(6), one O(7), and one O(8) atom. The Sr(3)-O(1) bond length is 2.92 Å. The Sr(3)-O(2) bond length is 2.60 Å. The Sr(3)-O(3) bond length is 2.59 Å. The Sr(3)-O(4) bond length is 2.49 Å. The Sr(3)-O(5) bond length is 2.60 Å. The Sr(3)-O(6) bond length is 2.81 Å. The Sr(3)-O(7) bond length is 2.48 Å. The Sr(3)-O(8) bond length is 2.71 Å. In the fourth Sr site, Sr(4) is bonded in a 7-coordinate geometry to one O(10), one O(11), one O(2), one O(4), one O(5), one O(7), and two equivalent O(9) atoms. The Sr(4)-O(10) bond length is 2.43 Å. The Sr(4)-O(11) bond length is 2.38 Å. The Sr(4)-O(2) bond length is 2.50 Å. The Sr(4)-O(4) bond length is 2.58 Å. The Sr(4)-O(5) bond length is 2.50 Å. The Sr(4)-O(7) bond length is 2.61 Å. There is one shorter (2.75 Å) and one longer (3.14 Å) Sr(4)-O(9) bond length. Mg(1) is bonded in a 5-coordinate geometry to one O(1), one O(11), one O(3), one O(6), and one O(8) atom. The Mg(1)-O(1) bond length is 2.10 Å. The Mg(1)-O(11) bond length is 2.09 Å. The Mg(1)-O(3) bond length is 2.03 Å. The Mg(1)-O(6) bond length is 2.11 Å. The Mg(1)-O(8) bond length is 2.00 Å. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(10), one O(2), one O(5), and one O(6) atom to form FeO5 square pyramids that share  a cornercorner with one Fe(2)O6 octahedra, corners with two equivalent Fe(3)O5 trigonal bipyramids, and corners with two equivalent Fe(4)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 30°. The Fe(1)-O(1) bond length is 2.03 Å. The Fe(1)-O(10) bond length is 1.91 Å. The Fe(1)-O(2) bond length is 2.01 Å. The Fe(1)-O(5) bond length is 2.01 Å. The Fe(1)-O(6) bond length is 2.01 Å. In the second Fe site, Fe(2) is bonded to one O(10), one O(11), one O(3), one O(4), one O(7), and one O(8) atom to form corner-sharing FeO6 octahedra. The Fe(2)-O(10) bond length is 2.00 Å. The Fe(2)-O(11) bond length is 1.94 Å. The Fe(2)-O(3) bond length is 1.95 Å. The Fe(2)-O(4) bond length is 2.19 Å. The Fe(2)-O(7) bond length is 1.98 Å. The Fe(2)-O(8) bond length is 2.31 Å. In the third Fe site, Fe(3) is bonded to one O(2), one O(4), one O(5), one O(7), and one O(9) atom to form distorted FeO5 trigonal bipyramids that share corners with two equivalent Fe(2)O6 octahedra, corners with two equivalent Fe(1)O5 square pyramids, and  a cornercorner with one Fe(4)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 26-27°. The Fe(3)-O(2) bond length is 2.01 Å. The Fe(3)-O(4) bond length is 1.97 Å. The Fe(3)-O(5) bond length is 2.01 Å. The Fe(3)-O(7) bond length is 2.00 Å. The Fe(3)-O(9) bond length is 2.05 Å. In the fourth Fe site, Fe(4) is bonded to one O(1), one O(3), one O(6), one O(8), and one O(9) atom to form distorted FeO5 trigonal bipyramids that share corners with two equivalent Fe(2)O6 octahedra, corners with two equivalent Fe(1)O5 square pyramids, and  a cornercorner with one Fe(3)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 36-37°. The Fe(4)-O(1) bond length is 2.01 Å. The Fe(4)-O(3) bond length is 2.08 Å. The Fe(4)-O(6) bond length is 1.98 Å. The Fe(4)-O(8) bond length is 1.96 Å. The Fe(4)-O(9) bond length is 2.04 Å. There are eleven inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to one Sr(1), one Sr(2), one Sr(3), one Mg(1), one Fe(1), and one Fe(4) atom. In the second O site, O(2) is bonded in a 6-coordinate geometry to one Sr(1), one Sr(2), one Sr(3), one Sr(4), one Fe(1), and one Fe(3) atom. In the third O site, O(3) is bonded in a distorted trigonal bipyramidal geometry to one Sr(1), one Sr(3), one Mg(1), one Fe(2), and one Fe(4) atom. In the fourth O site, O(4) is bonded in a 6-coordinate geometry to one Sr(1), one Sr(2), one Sr(3), one Sr(4), one Fe(2), and one Fe(3) atom. In the fifth O site, O(5) is bonded in a 5-coordinate geometry to one Sr(1), one Sr(3), one Sr(4), one Fe(1), and one Fe(3) atom. In the sixth O site, O(6) is bonded in a distorted T-shaped geometry to one Sr(1), one Sr(2), one Sr(3), one Mg(1), one Fe(1), and one Fe(4) atom. In the seventh O site, O(7) is bonded in a 5-coordinate geometry to one Sr(1), one Sr(2), one Sr(3), one Sr(4), one Fe(2), and one Fe(3) atom. In the eighth O site, O(8) is bonded in a 5-coordinate geometry to one Sr(1), one Sr(3), one Mg(1), one Fe(2), and one Fe(4) atom. In the ninth O site, O(9) is bonded in a 6-coordinate geometry to one Sr(1), one Sr(2), two equivalent Sr(4), 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(4), two equivalent Sr(1), one Fe(1), and one Fe(2) atom. In the eleventh O site, O(11) is bonded in a 4-coordinate geometry to one Sr(2), one Sr(4), one Mg(1), and one Fe(2) atom.