NdSr2Mn2O7 crystallizes in the tetragonal I4mm space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to four equivalent O(3), four equivalent O(4), and four equivalent O(5) atoms to form SrO12 cuboctahedra that share corners with four equivalent Sr(1)O12 cuboctahedra, faces with four equivalent Sr(1)O12 cuboctahedra, faces with four equivalent Mn(1)O6 octahedra, and faces with four equivalent Mn(2)O6 octahedra. In the second Sr site, Sr(2) is bonded in a 9-coordinate geometry to one O(1), four equivalent O(2), and four equivalent O(4) atoms. Nd(1) is bonded in a 9-coordinate geometry to one O(2), four equivalent O(1), and four equivalent O(3) atoms. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one O(1), one O(5), and four equivalent O(3) atoms to form MnO6 octahedra that share  a cornercorner with one Mn(2)O6 octahedra, corners with four equivalent Mn(1)O6 octahedra, and faces with four equivalent Sr(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-9°. In the second Mn site, Mn(2) is bonded to one O(2), one O(5), and four equivalent O(4) atoms to form MnO6 octahedra that share  a cornercorner with one Mn(1)O6 octahedra, corners with four equivalent Mn(2)O6 octahedra, and faces with four equivalent Sr(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-2°. There are five inequivalent O sites. In the first O site, O(1) is bonded to one Sr(2), four equivalent Nd(1), and one Mn(1) atom to form distorted OSrNd4Mn octahedra that share corners with four equivalent O(4)Sr4Mn2 octahedra, corners with four equivalent O(1)SrNd4Mn octahedra, edges with four equivalent O(2)Sr4NdMn octahedra, and edges with four equivalent O(1)SrNd4Mn octahedra. The corner-sharing octahedral tilt angles range from 12-49°. In the second O site, O(2) is bonded to four equivalent Sr(2), one Nd(1), and one Mn(2) atom to form distorted OSr4NdMn octahedra that share corners with four equivalent O(2)Sr4NdMn octahedra, corners with eight equivalent O(4)Sr4Mn2 octahedra, edges with four equivalent O(2)Sr4NdMn octahedra, edges with four equivalent O(1)SrNd4Mn octahedra, and faces with four equivalent O(4)Sr4Mn2 octahedra. The corner-sharing octahedral tilt angles range from 17-52°. In the third O site, O(3) is bonded in a 6-coordinate geometry to two equivalent Sr(1), two equivalent Nd(1), and two equivalent Mn(1) atoms. In the fourth O site, O(4) is bonded to two equivalent Sr(1), two equivalent Sr(2), and two equivalent Mn(2) atoms to form distorted OSr4Mn2 octahedra that share corners with two equivalent O(4)Sr4Mn2 octahedra, corners with two equivalent O(1)SrNd4Mn octahedra, corners with four equivalent O(2)Sr4NdMn octahedra, edges with two equivalent O(4)Sr4Mn2 octahedra, faces with two equivalent O(2)Sr4NdMn octahedra, and faces with four equivalent O(4)Sr4Mn2 octahedra. The corner-sharing octahedral tilt angles range from 2-52°. In the fifth O site, O(5) is bonded in a distorted linear geometry to four equivalent Sr(1), one Mn(1), and one Mn(2) atom.
NdSr2Mn2O7 crystallizes in the tetragonal I4mm space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to four equivalent O(3), four equivalent O(4), and four equivalent O(5) atoms to form SrO12 cuboctahedra that share corners with four equivalent Sr(1)O12 cuboctahedra, faces with four equivalent Sr(1)O12 cuboctahedra, faces with four equivalent Mn(1)O6 octahedra, and faces with four equivalent Mn(2)O6 octahedra. All Sr(1)-O(3) bond lengths are 2.95 Å. All Sr(1)-O(4) bond lengths are 2.70 Å. All Sr(1)-O(5) bond lengths are 2.77 Å. In the second Sr site, Sr(2) is bonded in a 9-coordinate geometry to one O(1), four equivalent O(2), and four equivalent O(4) atoms. The Sr(2)-O(1) bond length is 2.45 Å. All Sr(2)-O(2) bond lengths are 2.80 Å. All Sr(2)-O(4) bond lengths are 2.60 Å. Nd(1) is bonded in a 9-coordinate geometry to one O(2), four equivalent O(1), and four equivalent O(3) atoms. The Nd(1)-O(2) bond length is 2.32 Å. All Nd(1)-O(1) bond lengths are 2.78 Å. All Nd(1)-O(3) bond lengths are 2.51 Å. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one O(1), one O(5), and four equivalent O(3) atoms to form MnO6 octahedra that share  a cornercorner with one Mn(2)O6 octahedra, corners with four equivalent Mn(1)O6 octahedra, and faces with four equivalent Sr(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-9°. The Mn(1)-O(1) bond length is 2.01 Å. The Mn(1)-O(5) bond length is 1.92 Å. All Mn(1)-O(3) bond lengths are 1.96 Å. In the second Mn site, Mn(2) is bonded to one O(2), one O(5), and four equivalent O(4) atoms to form MnO6 octahedra that share  a cornercorner with one Mn(1)O6 octahedra, corners with four equivalent Mn(2)O6 octahedra, and faces with four equivalent Sr(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-2°. The Mn(2)-O(2) bond length is 2.09 Å. The Mn(2)-O(5) bond length is 2.03 Å. All Mn(2)-O(4) bond lengths are 1.96 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded to one Sr(2), four equivalent Nd(1), and one Mn(1) atom to form distorted OSrNd4Mn octahedra that share corners with four equivalent O(4)Sr4Mn2 octahedra, corners with four equivalent O(1)SrNd4Mn octahedra, edges with four equivalent O(2)Sr4NdMn octahedra, and edges with four equivalent O(1)SrNd4Mn octahedra. The corner-sharing octahedral tilt angles range from 12-49°. In the second O site, O(2) is bonded to four equivalent Sr(2), one Nd(1), and one Mn(2) atom to form distorted OSr4NdMn octahedra that share corners with four equivalent O(2)Sr4NdMn octahedra, corners with eight equivalent O(4)Sr4Mn2 octahedra, edges with four equivalent O(2)Sr4NdMn octahedra, edges with four equivalent O(1)SrNd4Mn octahedra, and faces with four equivalent O(4)Sr4Mn2 octahedra. The corner-sharing octahedral tilt angles range from 17-52°. In the third O site, O(3) is bonded in a 6-coordinate geometry to two equivalent Sr(1), two equivalent Nd(1), and two equivalent Mn(1) atoms. In the fourth O site, O(4) is bonded to two equivalent Sr(1), two equivalent Sr(2), and two equivalent Mn(2) atoms to form distorted OSr4Mn2 octahedra that share corners with two equivalent O(4)Sr4Mn2 octahedra, corners with two equivalent O(1)SrNd4Mn octahedra, corners with four equivalent O(2)Sr4NdMn octahedra, edges with two equivalent O(4)Sr4Mn2 octahedra, faces with two equivalent O(2)Sr4NdMn octahedra, and faces with four equivalent O(4)Sr4Mn2 octahedra. The corner-sharing octahedral tilt angles range from 2-52°. In the fifth O site, O(5) is bonded in a distorted linear geometry to four equivalent Sr(1), one Mn(1), and one Mn(2) atom.