Sr4MgMn2(GaO5)2 crystallizes in the triclinic P-1 space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 6-coordinate geometry to one O(1), one O(3), one O(4), one O(5), and two equivalent O(2) atoms. In the second Sr site, Sr(2) is bonded in a distorted pentagonal planar geometry to one O(1), one O(3), one O(5), and two equivalent O(4) atoms. Mg(1) is bonded in a square co-planar geometry to two equivalent O(1) and two equivalent O(2) atoms. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form MnO6 octahedra that share corners with two equivalent Ga(1)O4 tetrahedra. In the second Mn site, Mn(2) is bonded in a square co-planar geometry to two equivalent O(1) and two equivalent O(2) atoms. Ga(1) is bonded to one O(3), one O(4), and two equivalent O(5) atoms to form GaO4 tetrahedra that share  a cornercorner with one Mn(1)O6 octahedra and  an edgeedge with one Ga(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 6°. There are five inequivalent O sites. In the first O site, O(1) is bonded to one Sr(1), one Sr(2), one Mg(1), one Mn(1), and one Mn(2) atom to form a mixture of distorted edge and corner-sharing OSr2MgMn2 trigonal bipyramids. In the second O site, O(2) is bonded to two equivalent Sr(1), one Mg(1), one Mn(1), and one Mn(2) atom to form a mixture of edge and corner-sharing OSr2MgMn2 trigonal bipyramids. In the third O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to one Sr(1), one Sr(2), one Mn(1), and one Ga(1) atom. In the fourth O site, O(4) is bonded in a distorted rectangular see-saw-like geometry to one Sr(1), two equivalent Sr(2), and one Ga(1) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Sr(1), one Sr(2), and two equivalent Ga(1) atoms.
Sr4MgMn2(GaO5)2 crystallizes in the triclinic P-1 space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 6-coordinate geometry to one O(1), one O(3), one O(4), one O(5), and two equivalent O(2) atoms. The Sr(1)-O(1) bond length is 2.78 Å. The Sr(1)-O(3) bond length is 2.62 Å. The Sr(1)-O(4) bond length is 2.42 Å. The Sr(1)-O(5) bond length is 2.82 Å. There is one shorter (2.55 Å) and one longer (2.56 Å) Sr(1)-O(2) bond length. In the second Sr site, Sr(2) is bonded in a distorted pentagonal planar geometry to one O(1), one O(3), one O(5), and two equivalent O(4) atoms. The Sr(2)-O(1) bond length is 2.52 Å. The Sr(2)-O(3) bond length is 2.56 Å. The Sr(2)-O(5) bond length is 2.47 Å. There is one shorter (2.43 Å) and one longer (2.54 Å) Sr(2)-O(4) bond length. Mg(1) is bonded in a square co-planar geometry to two equivalent O(1) and two equivalent O(2) atoms. Both Mg(1)-O(1) bond lengths are 2.04 Å. Both Mg(1)-O(2) bond lengths are 2.05 Å. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form MnO6 octahedra that share corners with two equivalent Ga(1)O4 tetrahedra. Both Mn(1)-O(1) bond lengths are 2.16 Å. Both Mn(1)-O(2) bond lengths are 2.31 Å. Both Mn(1)-O(3) bond lengths are 2.33 Å. In the second Mn site, Mn(2) is bonded in a square co-planar geometry to two equivalent O(1) and two equivalent O(2) atoms. Both Mn(2)-O(1) bond lengths are 2.04 Å. Both Mn(2)-O(2) bond lengths are 2.19 Å. Ga(1) is bonded to one O(3), one O(4), and two equivalent O(5) atoms to form GaO4 tetrahedra that share  a cornercorner with one Mn(1)O6 octahedra and  an edgeedge with one Ga(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 6°. The Ga(1)-O(3) bond length is 1.84 Å. The Ga(1)-O(4) bond length is 1.84 Å. There is one shorter (1.91 Å) and one longer (1.94 Å) Ga(1)-O(5) bond length. There are five inequivalent O sites. In the first O site, O(1) is bonded to one Sr(1), one Sr(2), one Mg(1), one Mn(1), and one Mn(2) atom to form a mixture of distorted edge and corner-sharing OSr2MgMn2 trigonal bipyramids. In the second O site, O(2) is bonded to two equivalent Sr(1), one Mg(1), one Mn(1), and one Mn(2) atom to form a mixture of edge and corner-sharing OSr2MgMn2 trigonal bipyramids. In the third O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to one Sr(1), one Sr(2), one Mn(1), and one Ga(1) atom. In the fourth O site, O(4) is bonded in a distorted rectangular see-saw-like geometry to one Sr(1), two equivalent Sr(2), and one Ga(1) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Sr(1), one Sr(2), and two equivalent Ga(1) atoms.