Sr4MgMn4O10 crystallizes in the monoclinic Cm space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 8-coordinate geometry to one O(4), one O(5), two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms. In the second Sr site, Sr(2) is bonded in a 9-coordinate geometry to one O(6), two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. Mg(1) is bonded to one O(5), one O(6), and two equivalent O(4) atoms to form distorted MgO4 tetrahedra that share corners with two equivalent Mn(2)O4 tetrahedra, corners with two equivalent Mn(3)O4 tetrahedra, and  an edgeedge with one Mn(3)O4 tetrahedra. There are three inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one O(3), two equivalent O(1), and two equivalent O(2) atoms to form distorted MnO5 square pyramids that share corners with four equivalent Mn(1)O5 square pyramids and  a cornercorner with one Mn(2)O4 tetrahedra. In the second Mn site, Mn(2) is bonded to one O(5), one O(6), and two equivalent O(3) atoms to form distorted MnO4 tetrahedra that share corners with two equivalent Mn(1)O5 square pyramids, corners with two equivalent Mg(1)O4 tetrahedra, and corners with two equivalent Mn(3)O4 tetrahedra. In the third Mn site, Mn(3) is bonded to one O(5), one O(6), and two equivalent O(4) atoms to form distorted MnO4 tetrahedra that share corners with two equivalent Mg(1)O4 tetrahedra, corners with two equivalent Mn(2)O4 tetrahedra, and  an edgeedge with one Mg(1)O4 tetrahedra. There are six inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Sr(1), two equivalent Sr(2), and two equivalent Mn(1) atoms to form distorted OSr4Mn2 octahedra that share corners with two equivalent O(1)Sr4Mn2 octahedra, corners with two equivalent O(6)Sr2MgMn2 square pyramids, corners with two equivalent O(5)Sr2MgMn2 trigonal bipyramids, edges with two equivalent O(1)Sr4Mn2 octahedra, and faces with four equivalent O(2)Sr4Mn2 octahedra. The corner-sharing octahedral tilt angles are 7°. In the second O site, O(2) is bonded to two equivalent Sr(1), two equivalent Sr(2), and two equivalent Mn(1) atoms to form OSr4Mn2 octahedra that share corners with two equivalent O(2)Sr4Mn2 octahedra, corners with two equivalent O(6)Sr2MgMn2 square pyramids, corners with two equivalent O(5)Sr2MgMn2 trigonal bipyramids, edges with two equivalent O(2)Sr4Mn2 octahedra, and faces with four equivalent O(1)Sr4Mn2 octahedra. The corner-sharing octahedral tilt angles are 7°. In the third O site, O(3) is bonded in a 6-coordinate geometry to two equivalent Sr(1), two equivalent Sr(2), one Mn(1), and one Mn(2) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one Sr(1), two equivalent Sr(2), one Mg(1), and one Mn(3) atom. In the fifth O site, O(5) is bonded to two equivalent Sr(1), one Mg(1), one Mn(2), and one Mn(3) atom to form OSr2MgMn2 trigonal bipyramids that share corners with four equivalent O(1)Sr4Mn2 octahedra, corners with four equivalent O(2)Sr4Mn2 octahedra, and corners with three equivalent O(6)Sr2MgMn2 square pyramids. The corner-sharing octahedral tilt angles range from 38-59°. In the sixth O site, O(6) is bonded to two equivalent Sr(2), one Mg(1), one Mn(2), and one Mn(3) atom to form OSr2MgMn2 square pyramids that share corners with four equivalent O(1)Sr4Mn2 octahedra, corners with four equivalent O(2)Sr4Mn2 octahedra, and corners with three equivalent O(5)Sr2MgMn2 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 42-55°.
Sr4MgMn4O10 crystallizes in the monoclinic Cm space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 8-coordinate geometry to one O(4), one O(5), two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms. The Sr(1)-O(4) bond length is 2.69 Å. The Sr(1)-O(5) bond length is 2.54 Å. There is one shorter (2.61 Å) and one longer (2.76 Å) Sr(1)-O(1) bond length. There is one shorter (2.64 Å) and one longer (2.65 Å) Sr(1)-O(2) bond length. There is one shorter (2.83 Å) and one longer (2.91 Å) Sr(1)-O(3) bond length. In the second Sr site, Sr(2) is bonded in a 9-coordinate geometry to one O(6), two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. The Sr(2)-O(6) bond length is 2.56 Å. There is one shorter (2.63 Å) and one longer (2.67 Å) Sr(2)-O(1) bond length. There is one shorter (2.58 Å) and one longer (2.62 Å) Sr(2)-O(2) bond length. There is one shorter (2.74 Å) and one longer (3.01 Å) Sr(2)-O(3) bond length. There is one shorter (2.67 Å) and one longer (3.26 Å) Sr(2)-O(4) bond length. Mg(1) is bonded to one O(5), one O(6), and two equivalent O(4) atoms to form distorted MgO4 tetrahedra that share corners with two equivalent Mn(2)O4 tetrahedra, corners with two equivalent Mn(3)O4 tetrahedra, and  an edgeedge with one Mn(3)O4 tetrahedra. The Mg(1)-O(5) bond length is 2.06 Å. The Mg(1)-O(6) bond length is 2.08 Å. Both Mg(1)-O(4) bond lengths are 2.00 Å. There are three inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one O(3), two equivalent O(1), and two equivalent O(2) atoms to form distorted MnO5 square pyramids that share corners with four equivalent Mn(1)O5 square pyramids and  a cornercorner with one Mn(2)O4 tetrahedra. The Mn(1)-O(3) bond length is 2.25 Å. There is one shorter (1.95 Å) and one longer (1.96 Å) Mn(1)-O(1) bond length. There is one shorter (2.01 Å) and one longer (2.02 Å) Mn(1)-O(2) bond length. In the second Mn site, Mn(2) is bonded to one O(5), one O(6), and two equivalent O(3) atoms to form distorted MnO4 tetrahedra that share corners with two equivalent Mn(1)O5 square pyramids, corners with two equivalent Mg(1)O4 tetrahedra, and corners with two equivalent Mn(3)O4 tetrahedra. The Mn(2)-O(5) bond length is 2.03 Å. The Mn(2)-O(6) bond length is 2.07 Å. Both Mn(2)-O(3) bond lengths are 1.99 Å. In the third Mn site, Mn(3) is bonded to one O(5), one O(6), and two equivalent O(4) atoms to form distorted MnO4 tetrahedra that share corners with two equivalent Mg(1)O4 tetrahedra, corners with two equivalent Mn(2)O4 tetrahedra, and  an edgeedge with one Mg(1)O4 tetrahedra. The Mn(3)-O(5) bond length is 2.18 Å. The Mn(3)-O(6) bond length is 2.09 Å. Both Mn(3)-O(4) bond lengths are 2.09 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Sr(1), two equivalent Sr(2), and two equivalent Mn(1) atoms to form distorted OSr4Mn2 octahedra that share corners with two equivalent O(1)Sr4Mn2 octahedra, corners with two equivalent O(6)Sr2MgMn2 square pyramids, corners with two equivalent O(5)Sr2MgMn2 trigonal bipyramids, edges with two equivalent O(1)Sr4Mn2 octahedra, and faces with four equivalent O(2)Sr4Mn2 octahedra. The corner-sharing octahedral tilt angles are 7°. In the second O site, O(2) is bonded to two equivalent Sr(1), two equivalent Sr(2), and two equivalent Mn(1) atoms to form OSr4Mn2 octahedra that share corners with two equivalent O(2)Sr4Mn2 octahedra, corners with two equivalent O(6)Sr2MgMn2 square pyramids, corners with two equivalent O(5)Sr2MgMn2 trigonal bipyramids, edges with two equivalent O(2)Sr4Mn2 octahedra, and faces with four equivalent O(1)Sr4Mn2 octahedra. The corner-sharing octahedral tilt angles are 7°. In the third O site, O(3) is bonded in a 6-coordinate geometry to two equivalent Sr(1), two equivalent Sr(2), one Mn(1), and one Mn(2) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one Sr(1), two equivalent Sr(2), one Mg(1), and one Mn(3) atom. In the fifth O site, O(5) is bonded to two equivalent Sr(1), one Mg(1), one Mn(2), and one Mn(3) atom to form OSr2MgMn2 trigonal bipyramids that share corners with four equivalent O(1)Sr4Mn2 octahedra, corners with four equivalent O(2)Sr4Mn2 octahedra, and corners with three equivalent O(6)Sr2MgMn2 square pyramids. The corner-sharing octahedral tilt angles range from 38-59°. In the sixth O site, O(6) is bonded to two equivalent Sr(2), one Mg(1), one Mn(2), and one Mn(3) atom to form OSr2MgMn2 square pyramids that share corners with four equivalent O(1)Sr4Mn2 octahedra, corners with four equivalent O(2)Sr4Mn2 octahedra, and corners with three equivalent O(5)Sr2MgMn2 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 42-55°.