Sm2Cr2Fe15 crystallizes in the trigonal R-3m space group. Sm(1) is bonded in a 19-coordinate geometry to one Cr(1), three equivalent Fe(2), six equivalent Fe(3), and nine equivalent Fe(1) atoms. Cr(1) is bonded in a 14-coordinate geometry to one Sm(1), one Cr(1), three equivalent Fe(1), three equivalent Fe(2), and six equivalent Fe(3) atoms. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to three equivalent Sm(1), one Cr(1), two equivalent Fe(1), two equivalent Fe(2), and four equivalent Fe(3) atoms to form FeSm3CrFe8 cuboctahedra that share corners with five equivalent Fe(2)Sm2Cr2Fe8 cuboctahedra, corners with eight equivalent Fe(3)Sm2Cr2Fe8 cuboctahedra, corners with ten equivalent Fe(1)Sm3CrFe8 cuboctahedra, edges with two equivalent Fe(3)Sm2Cr2Fe8 cuboctahedra, edges with three equivalent Fe(2)Sm2Cr2Fe8 cuboctahedra, edges with five equivalent Fe(1)Sm3CrFe8 cuboctahedra, faces with three equivalent Fe(2)Sm2Cr2Fe8 cuboctahedra, faces with seven equivalent Fe(1)Sm3CrFe8 cuboctahedra, and faces with ten equivalent Fe(3)Sm2Cr2Fe8 cuboctahedra. In the second Fe site, Fe(2) is bonded to two equivalent Sm(1), two equivalent Cr(1), four equivalent Fe(1), and four equivalent Fe(3) atoms to form distorted FeSm2Cr2Fe8 cuboctahedra that share corners with four equivalent Fe(2)Sm2Cr2Fe8 cuboctahedra, corners with eight equivalent Fe(3)Sm2Cr2Fe8 cuboctahedra, corners with ten equivalent Fe(1)Sm3CrFe8 cuboctahedra, edges with four equivalent Fe(3)Sm2Cr2Fe8 cuboctahedra, edges with six equivalent Fe(1)Sm3CrFe8 cuboctahedra, faces with four equivalent Fe(2)Sm2Cr2Fe8 cuboctahedra, faces with six equivalent Fe(1)Sm3CrFe8 cuboctahedra, and faces with eight equivalent Fe(3)Sm2Cr2Fe8 cuboctahedra. In the third Fe site, Fe(3) is bonded to two equivalent Sm(1), two equivalent Cr(1), two equivalent Fe(2), two equivalent Fe(3), and four equivalent Fe(1) atoms to form distorted FeSm2Cr2Fe8 cuboctahedra that share corners with four equivalent Fe(2)Sm2Cr2Fe8 cuboctahedra, corners with eight equivalent Fe(1)Sm3CrFe8 cuboctahedra, corners with twelve equivalent Fe(3)Sm2Cr2Fe8 cuboctahedra,  an edgeedge with one Fe(3)Sm2Cr2Fe8 cuboctahedra, edges with two equivalent Fe(2)Sm2Cr2Fe8 cuboctahedra, edges with two equivalent Fe(1)Sm3CrFe8 cuboctahedra, faces with four equivalent Fe(2)Sm2Cr2Fe8 cuboctahedra, faces with seven equivalent Fe(3)Sm2Cr2Fe8 cuboctahedra, and faces with ten equivalent Fe(1)Sm3CrFe8 cuboctahedra.
Sm2Cr2Fe15 crystallizes in the trigonal R-3m space group. Sm(1) is bonded in a 19-coordinate geometry to one Cr(1), three equivalent Fe(2), six equivalent Fe(3), and nine equivalent Fe(1) atoms. The Sm(1)-Cr(1) bond length is 3.20 Å. All Sm(1)-Fe(2) bond lengths are 3.28 Å. All Sm(1)-Fe(3) bond lengths are 2.97 Å. There are a spread of Sm(1)-Fe(1) bond distances ranging from 3.09-3.21 Å. Cr(1) is bonded in a 14-coordinate geometry to one Sm(1), one Cr(1), three equivalent Fe(1), three equivalent Fe(2), and six equivalent Fe(3) atoms. The Cr(1)-Cr(1) bond length is 2.15 Å. All Cr(1)-Fe(1) bond lengths are 2.64 Å. All Cr(1)-Fe(2) bond lengths are 2.63 Å. All Cr(1)-Fe(3) bond lengths are 2.73 Å. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to three equivalent Sm(1), one Cr(1), two equivalent Fe(1), two equivalent Fe(2), and four equivalent Fe(3) atoms to form FeSm3CrFe8 cuboctahedra that share corners with five equivalent Fe(2)Sm2Cr2Fe8 cuboctahedra, corners with eight equivalent Fe(3)Sm2Cr2Fe8 cuboctahedra, corners with ten equivalent Fe(1)Sm3CrFe8 cuboctahedra, edges with two equivalent Fe(3)Sm2Cr2Fe8 cuboctahedra, edges with three equivalent Fe(2)Sm2Cr2Fe8 cuboctahedra, edges with five equivalent Fe(1)Sm3CrFe8 cuboctahedra, faces with three equivalent Fe(2)Sm2Cr2Fe8 cuboctahedra, faces with seven equivalent Fe(1)Sm3CrFe8 cuboctahedra, and faces with ten equivalent Fe(3)Sm2Cr2Fe8 cuboctahedra. Both Fe(1)-Fe(1) bond lengths are 2.47 Å. Both Fe(1)-Fe(2) bond lengths are 2.42 Å. There are two shorter (2.52 Å) and two longer (2.62 Å) Fe(1)-Fe(3) bond lengths. In the second Fe site, Fe(2) is bonded to two equivalent Sm(1), two equivalent Cr(1), four equivalent Fe(1), and four equivalent Fe(3) atoms to form distorted FeSm2Cr2Fe8 cuboctahedra that share corners with four equivalent Fe(2)Sm2Cr2Fe8 cuboctahedra, corners with eight equivalent Fe(3)Sm2Cr2Fe8 cuboctahedra, corners with ten equivalent Fe(1)Sm3CrFe8 cuboctahedra, edges with four equivalent Fe(3)Sm2Cr2Fe8 cuboctahedra, edges with six equivalent Fe(1)Sm3CrFe8 cuboctahedra, faces with four equivalent Fe(2)Sm2Cr2Fe8 cuboctahedra, faces with six equivalent Fe(1)Sm3CrFe8 cuboctahedra, and faces with eight equivalent Fe(3)Sm2Cr2Fe8 cuboctahedra. All Fe(2)-Fe(3) bond lengths are 2.44 Å. In the third Fe site, Fe(3) is bonded to two equivalent Sm(1), two equivalent Cr(1), two equivalent Fe(2), two equivalent Fe(3), and four equivalent Fe(1) atoms to form distorted FeSm2Cr2Fe8 cuboctahedra that share corners with four equivalent Fe(2)Sm2Cr2Fe8 cuboctahedra, corners with eight equivalent Fe(1)Sm3CrFe8 cuboctahedra, corners with twelve equivalent Fe(3)Sm2Cr2Fe8 cuboctahedra,  an edgeedge with one Fe(3)Sm2Cr2Fe8 cuboctahedra, edges with two equivalent Fe(2)Sm2Cr2Fe8 cuboctahedra, edges with two equivalent Fe(1)Sm3CrFe8 cuboctahedra, faces with four equivalent Fe(2)Sm2Cr2Fe8 cuboctahedra, faces with seven equivalent Fe(3)Sm2Cr2Fe8 cuboctahedra, and faces with ten equivalent Fe(1)Sm3CrFe8 cuboctahedra. Both Fe(3)-Fe(3) bond lengths are 2.51 Å.