Sr8Mn2FeN8 crystallizes in the monoclinic C2/m space group. There are four inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to one N(1), two equivalent N(3), and two equivalent N(4) atoms to form a mixture of distorted corner and edge-sharing SrN5 trigonal bipyramids. In the second Sr site, Sr(2) is bonded in a 5-coordinate geometry to one N(1), one N(4), and three equivalent N(2) atoms. In the third Sr site, Sr(3) is bonded to one N(2), two equivalent N(3), and two equivalent N(4) atoms to form a mixture of distorted corner and edge-sharing SrN5 square pyramids. In the fourth Sr site, Sr(4) is bonded to one N(2), one N(3), and three equivalent N(1) atoms to form a mixture of distorted corner and edge-sharing SrN5 trigonal bipyramids. Mn(1) is bonded in a trigonal planar geometry to one N(1), one N(2), and one N(3) atom. Fe(1) is bonded in a linear geometry to two equivalent N(4) atoms. There are four inequivalent N sites. In the first N site, N(1) is bonded to one Sr(1), one Sr(2), three equivalent Sr(4), and one Mn(1) atom to form distorted NSr5Mn octahedra that share corners with two equivalent N(1)Sr5Mn octahedra, corners with three equivalent N(4)Sr5Fe octahedra, edges with two equivalent N(1)Sr5Mn octahedra, and edges with three equivalent N(3)Sr5Mn octahedra. The corner-sharing octahedral tilt angles range from 19-66°. In the second N site, N(2) is bonded in a distorted single-bond geometry to one Sr(3), one Sr(4), three equivalent Sr(2), and one Mn(1) atom. In the third N site, N(3) is bonded to one Sr(4), two equivalent Sr(1), two equivalent Sr(3), and one Mn(1) atom to form distorted NSr5Mn octahedra that share corners with two equivalent N(3)Sr5Mn octahedra,  an edgeedge with one N(3)Sr5Mn octahedra, edges with three equivalent N(1)Sr5Mn octahedra, and edges with four equivalent N(4)Sr5Fe octahedra. The corner-sharing octahedral tilt angles are 16°. In the fourth N site, N(4) is bonded to one Sr(2), two equivalent Sr(1), two equivalent Sr(3), and one Fe(1) atom to form distorted NSr5Fe octahedra that share corners with three equivalent N(4)Sr5Fe octahedra, corners with three equivalent N(1)Sr5Mn octahedra,  an edgeedge with one N(4)Sr5Fe octahedra, and edges with four equivalent N(3)Sr5Mn octahedra. The corner-sharing octahedral tilt angles range from 0-66°.
Sr8Mn2FeN8 crystallizes in the monoclinic C2/m space group. There are four inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to one N(1), two equivalent N(3), and two equivalent N(4) atoms to form a mixture of distorted corner and edge-sharing SrN5 trigonal bipyramids. The Sr(1)-N(1) bond length is 2.89 Å. Both Sr(1)-N(3) bond lengths are 2.70 Å. There is one shorter (2.53 Å) and one longer (3.05 Å) Sr(1)-N(4) bond length. In the second Sr site, Sr(2) is bonded in a 5-coordinate geometry to one N(1), one N(4), and three equivalent N(2) atoms. The Sr(2)-N(1) bond length is 2.64 Å. The Sr(2)-N(4) bond length is 2.65 Å. There are two shorter (2.70 Å) and one longer (2.81 Å) Sr(2)-N(2) bond length. In the third Sr site, Sr(3) is bonded to one N(2), two equivalent N(3), and two equivalent N(4) atoms to form a mixture of distorted corner and edge-sharing SrN5 square pyramids. The Sr(3)-N(2) bond length is 2.74 Å. There is one shorter (2.67 Å) and one longer (2.82 Å) Sr(3)-N(3) bond length. Both Sr(3)-N(4) bond lengths are 2.68 Å. In the fourth Sr site, Sr(4) is bonded to one N(2), one N(3), and three equivalent N(1) atoms to form a mixture of distorted corner and edge-sharing SrN5 trigonal bipyramids. The Sr(4)-N(2) bond length is 2.79 Å. The Sr(4)-N(3) bond length is 2.64 Å. There are two shorter (2.71 Å) and one longer (2.74 Å) Sr(4)-N(1) bond length. Mn(1) is bonded in a trigonal planar geometry to one N(1), one N(2), and one N(3) atom. The Mn(1)-N(1) bond length is 1.75 Å. The Mn(1)-N(2) bond length is 1.73 Å. The Mn(1)-N(3) bond length is 1.78 Å. Fe(1) is bonded in a linear geometry to two equivalent N(4) atoms. Both Fe(1)-N(4) bond lengths are 1.84 Å. There are four inequivalent N sites. In the first N site, N(1) is bonded to one Sr(1), one Sr(2), three equivalent Sr(4), and one Mn(1) atom to form distorted NSr5Mn octahedra that share corners with two equivalent N(1)Sr5Mn octahedra, corners with three equivalent N(4)Sr5Fe octahedra, edges with two equivalent N(1)Sr5Mn octahedra, and edges with three equivalent N(3)Sr5Mn octahedra. The corner-sharing octahedral tilt angles range from 19-66°. In the second N site, N(2) is bonded in a distorted single-bond geometry to one Sr(3), one Sr(4), three equivalent Sr(2), and one Mn(1) atom. In the third N site, N(3) is bonded to one Sr(4), two equivalent Sr(1), two equivalent Sr(3), and one Mn(1) atom to form distorted NSr5Mn octahedra that share corners with two equivalent N(3)Sr5Mn octahedra,  an edgeedge with one N(3)Sr5Mn octahedra, edges with three equivalent N(1)Sr5Mn octahedra, and edges with four equivalent N(4)Sr5Fe octahedra. The corner-sharing octahedral tilt angles are 16°. In the fourth N site, N(4) is bonded to one Sr(2), two equivalent Sr(1), two equivalent Sr(3), and one Fe(1) atom to form distorted NSr5Fe octahedra that share corners with three equivalent N(4)Sr5Fe octahedra, corners with three equivalent N(1)Sr5Mn octahedra,  an edgeedge with one N(4)Sr5Fe octahedra, and edges with four equivalent N(3)Sr5Mn octahedra. The corner-sharing octahedral tilt angles range from 0-66°.