Sr4MgMn3(O4Cl)2 crystallizes in the monoclinic Cm space group. There are four inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 8-coordinate geometry to four equivalent O(1) and four equivalent Cl(1) atoms. In the second Sr site, Sr(2) is bonded in a 10-coordinate geometry to one Mg(1), four equivalent O(2), one Cl(1), and four equivalent Cl(2) atoms. In the third Sr site, Sr(3) is bonded to four equivalent O(1), four equivalent O(3), and four equivalent O(4) atoms to form SrO12 cuboctahedra that share corners with four equivalent Sr(3)O12 cuboctahedra, faces with four equivalent Sr(3)O12 cuboctahedra, faces with four equivalent Mn(1)O6 octahedra, and faces with four equivalent Mn(3)O5 square pyramids. In the fourth Sr site, Sr(4) is bonded in a 8-coordinate geometry to four equivalent O(3) and four equivalent O(5) atoms. Mg(1) is bonded in a distorted square co-planar geometry to one Sr(2) and four equivalent O(2) atoms. There are three inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one O(4), one O(5), and four equivalent O(3) atoms to form MnO6 octahedra that share corners with four equivalent Mn(1)O6 octahedra,  a cornercorner with one Mn(3)O5 square pyramid, and faces with four equivalent Sr(3)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 1°. In the second Mn site, Mn(2) is bonded in a 5-coordinate geometry to one O(5) and four equivalent O(2) atoms. In the third Mn site, Mn(3) is bonded to one O(4) and four equivalent O(1) atoms to form MnO5 square pyramids that share  a cornercorner with one Mn(1)O6 octahedra, corners with four equivalent Mn(3)O5 square pyramids, and faces with four equivalent Sr(3)O12 cuboctahedra. The corner-sharing octahedra are not tilted. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to two equivalent Sr(1), two equivalent Sr(3), and two equivalent Mn(3) atoms. In the second O site, O(2) is bonded in a distorted see-saw-like geometry to two equivalent Sr(2), two equivalent Mg(1), and two equivalent Mn(2) atoms. In the third O site, O(3) is bonded to two equivalent Sr(3), two equivalent Sr(4), and two equivalent Mn(1) atoms to form a mixture of distorted corner, edge, and face-sharing OSr4Mn2 octahedra. The corner-sharing octahedral tilt angles are 1°. In the fourth O site, O(4) is bonded in a distorted linear geometry to four equivalent Sr(3), one Mn(1), and one Mn(3) atom. In the fifth O site, O(5) is bonded in a 6-coordinate geometry to four equivalent Sr(4), one Mn(1), and one Mn(2) atom. There are two inequivalent Cl sites. In the first Cl site, Cl(1) is bonded in a 5-coordinate geometry to one Sr(2) and four equivalent Sr(1) atoms. In the second Cl site, Cl(2) is bonded in a distorted square co-planar geometry to four equivalent Sr(2) atoms.
Sr4MgMn3(O4Cl)2 crystallizes in the monoclinic Cm space group. There are four inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 8-coordinate geometry to four equivalent O(1) and four equivalent Cl(1) atoms. All Sr(1)-O(1) bond lengths are 2.46 Å. There are three shorter (3.24 Å) and one longer (3.25 Å) Sr(1)-Cl(1) bond length. In the second Sr site, Sr(2) is bonded in a 10-coordinate geometry to one Mg(1), four equivalent O(2), one Cl(1), and four equivalent Cl(2) atoms. The Sr(2)-Mg(1) bond length is 2.83 Å. There are two shorter (3.20 Å) and two longer (3.21 Å) Sr(2)-O(2) bond lengths. The Sr(2)-Cl(1) bond length is 2.91 Å. All Sr(2)-Cl(2) bond lengths are 2.91 Å. In the third Sr site, Sr(3) is bonded to four equivalent O(1), four equivalent O(3), and four equivalent O(4) atoms to form SrO12 cuboctahedra that share corners with four equivalent Sr(3)O12 cuboctahedra, faces with four equivalent Sr(3)O12 cuboctahedra, faces with four equivalent Mn(1)O6 octahedra, and faces with four equivalent Mn(3)O5 square pyramids. All Sr(3)-O(1) bond lengths are 3.10 Å. All Sr(3)-O(3) bond lengths are 2.79 Å. All Sr(3)-O(4) bond lengths are 2.83 Å. In the fourth Sr site, Sr(4) is bonded in a 8-coordinate geometry to four equivalent O(3) and four equivalent O(5) atoms. All Sr(4)-O(3) bond lengths are 2.52 Å. All Sr(4)-O(5) bond lengths are 2.91 Å. Mg(1) is bonded in a distorted square co-planar geometry to one Sr(2) and four equivalent O(2) atoms. All Mg(1)-O(2) bond lengths are 2.03 Å. There are three inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one O(4), one O(5), and four equivalent O(3) atoms to form MnO6 octahedra that share corners with four equivalent Mn(1)O6 octahedra,  a cornercorner with one Mn(3)O5 square pyramid, and faces with four equivalent Sr(3)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 1°. The Mn(1)-O(4) bond length is 1.95 Å. The Mn(1)-O(5) bond length is 2.24 Å. All Mn(1)-O(3) bond lengths are 2.00 Å. In the second Mn site, Mn(2) is bonded in a 5-coordinate geometry to one O(5) and four equivalent O(2) atoms. The Mn(2)-O(5) bond length is 2.04 Å. All Mn(2)-O(2) bond lengths are 2.19 Å. In the third Mn site, Mn(3) is bonded to one O(4) and four equivalent O(1) atoms to form MnO5 square pyramids that share  a cornercorner with one Mn(1)O6 octahedra, corners with four equivalent Mn(3)O5 square pyramids, and faces with four equivalent Sr(3)O12 cuboctahedra. The corner-sharing octahedra are not tilted. The Mn(3)-O(4) bond length is 1.98 Å. All Mn(3)-O(1) bond lengths are 2.03 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to two equivalent Sr(1), two equivalent Sr(3), and two equivalent Mn(3) atoms. In the second O site, O(2) is bonded in a distorted see-saw-like geometry to two equivalent Sr(2), two equivalent Mg(1), and two equivalent Mn(2) atoms. In the third O site, O(3) is bonded to two equivalent Sr(3), two equivalent Sr(4), and two equivalent Mn(1) atoms to form a mixture of distorted corner, edge, and face-sharing OSr4Mn2 octahedra. The corner-sharing octahedral tilt angles are 1°. In the fourth O site, O(4) is bonded in a distorted linear geometry to four equivalent Sr(3), one Mn(1), and one Mn(3) atom. In the fifth O site, O(5) is bonded in a 6-coordinate geometry to four equivalent Sr(4), one Mn(1), and one Mn(2) atom. There are two inequivalent Cl sites. In the first Cl site, Cl(1) is bonded in a 5-coordinate geometry to one Sr(2) and four equivalent Sr(1) atoms. In the second Cl site, Cl(2) is bonded in a distorted square co-planar geometry to four equivalent Sr(2) atoms.