Sm2CrFe16 crystallizes in the trigonal R3m space group. There are two inequivalent Sm sites. In the first Sm site, Sm(1) is bonded in a 19-coordinate geometry to one Fe(5), three equivalent Fe(2), three equivalent Fe(3), six equivalent Fe(1), and six equivalent Fe(4) atoms. In the second Sm site, Sm(2) is bonded in a 19-coordinate geometry to one Cr(1), three equivalent Fe(2), three equivalent Fe(4), six equivalent Fe(1), and six equivalent Fe(3) atoms. Cr(1) is bonded in a 14-coordinate geometry to one Sm(2), one Fe(5), three equivalent Fe(2), three equivalent Fe(3), and six equivalent Fe(1) atoms. There are five inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 12-coordinate geometry to one Sm(1), one Sm(2), one Cr(1), one Fe(5), two equivalent Fe(1), two equivalent Fe(2), two equivalent Fe(3), and two equivalent Fe(4) atoms. In the second Fe site, Fe(2) is bonded to one Sm(1), one Sm(2), one Cr(1), one Fe(5), two equivalent Fe(3), two equivalent Fe(4), and four equivalent Fe(1) atoms to form distorted FeSm2CrFe9 cuboctahedra that share corners with four equivalent Fe(2)Sm2CrFe9 cuboctahedra, corners with five equivalent Fe(3)Sm3CrFe8 cuboctahedra, corners with five equivalent Fe(4)Sm3Fe9 cuboctahedra, edges with three equivalent Fe(3)Sm3CrFe8 cuboctahedra, edges with three equivalent Fe(4)Sm3Fe9 cuboctahedra, faces with three equivalent Fe(3)Sm3CrFe8 cuboctahedra, faces with three equivalent Fe(4)Sm3Fe9 cuboctahedra, and faces with four equivalent Fe(2)Sm2CrFe9 cuboctahedra. In the third Fe site, Fe(3) is bonded to one Sm(1), two equivalent Sm(2), one Cr(1), two equivalent Fe(2), two equivalent Fe(4), and four equivalent Fe(1) atoms to form FeSm3CrFe8 cuboctahedra that share corners with two equivalent Fe(3)Sm3CrFe8 cuboctahedra, corners with five equivalent Fe(2)Sm2CrFe9 cuboctahedra, corners with eight equivalent Fe(4)Sm3Fe9 cuboctahedra,  an edgeedge with one Fe(4)Sm3Fe9 cuboctahedra, edges with three equivalent Fe(2)Sm2CrFe9 cuboctahedra, edges with four equivalent Fe(3)Sm3CrFe8 cuboctahedra, faces with three equivalent Fe(2)Sm2CrFe9 cuboctahedra, faces with three equivalent Fe(4)Sm3Fe9 cuboctahedra, and faces with four equivalent Fe(3)Sm3CrFe8 cuboctahedra. In the fourth Fe site, Fe(4) is bonded to one Sm(2), two equivalent Sm(1), one Fe(5), two equivalent Fe(2), two equivalent Fe(3), and four equivalent Fe(1) atoms to form FeSm3Fe9 cuboctahedra that share corners with two equivalent Fe(4)Sm3Fe9 cuboctahedra, corners with five equivalent Fe(2)Sm2CrFe9 cuboctahedra, corners with eight equivalent Fe(3)Sm3CrFe8 cuboctahedra,  an edgeedge with one Fe(3)Sm3CrFe8 cuboctahedra, edges with three equivalent Fe(2)Sm2CrFe9 cuboctahedra, edges with four equivalent Fe(4)Sm3Fe9 cuboctahedra, faces with three equivalent Fe(2)Sm2CrFe9 cuboctahedra, faces with three equivalent Fe(3)Sm3CrFe8 cuboctahedra, and faces with four equivalent Fe(4)Sm3Fe9 cuboctahedra. In the fifth Fe site, Fe(5) is bonded in a distorted single-bond geometry to one Sm(1), one Cr(1), three equivalent Fe(2), three equivalent Fe(4), and six equivalent Fe(1) atoms.
Sm2CrFe16 crystallizes in the trigonal R3m space group. There are two inequivalent Sm sites. In the first Sm site, Sm(1) is bonded in a 19-coordinate geometry to one Fe(5), three equivalent Fe(2), three equivalent Fe(3), six equivalent Fe(1), and six equivalent Fe(4) atoms. The Sm(1)-Fe(5) bond length is 3.11 Å. All Sm(1)-Fe(2) bond lengths are 3.30 Å. All Sm(1)-Fe(3) bond lengths are 3.10 Å. All Sm(1)-Fe(1) bond lengths are 3.01 Å. There are three shorter (3.21 Å) and three longer (3.23 Å) Sm(1)-Fe(4) bond lengths. In the second Sm site, Sm(2) is bonded in a 19-coordinate geometry to one Cr(1), three equivalent Fe(2), three equivalent Fe(4), six equivalent Fe(1), and six equivalent Fe(3) atoms. The Sm(2)-Cr(1) bond length is 3.18 Å. All Sm(2)-Fe(2) bond lengths are 3.31 Å. All Sm(2)-Fe(4) bond lengths are 3.07 Å. All Sm(2)-Fe(1) bond lengths are 3.01 Å. There are three shorter (3.20 Å) and three longer (3.24 Å) Sm(2)-Fe(3) bond lengths. Cr(1) is bonded in a 14-coordinate geometry to one Sm(2), one Fe(5), three equivalent Fe(2), three equivalent Fe(3), and six equivalent Fe(1) atoms. The Cr(1)-Fe(5) bond length is 2.31 Å. All Cr(1)-Fe(2) bond lengths are 2.62 Å. All Cr(1)-Fe(3) bond lengths are 2.65 Å. All Cr(1)-Fe(1) bond lengths are 2.76 Å. There are five inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 12-coordinate geometry to one Sm(1), one Sm(2), one Cr(1), one Fe(5), two equivalent Fe(1), two equivalent Fe(2), two equivalent Fe(3), and two equivalent Fe(4) atoms. The Fe(1)-Fe(5) bond length is 2.76 Å. Both Fe(1)-Fe(1) bond lengths are 2.51 Å. There is one shorter (2.44 Å) and one longer (2.46 Å) Fe(1)-Fe(2) bond length. There is one shorter (2.55 Å) and one longer (2.63 Å) Fe(1)-Fe(3) bond length. There is one shorter (2.54 Å) and one longer (2.64 Å) Fe(1)-Fe(4) bond length. In the second Fe site, Fe(2) is bonded to one Sm(1), one Sm(2), one Cr(1), one Fe(5), two equivalent Fe(3), two equivalent Fe(4), and four equivalent Fe(1) atoms to form distorted FeSm2CrFe9 cuboctahedra that share corners with four equivalent Fe(2)Sm2CrFe9 cuboctahedra, corners with five equivalent Fe(3)Sm3CrFe8 cuboctahedra, corners with five equivalent Fe(4)Sm3Fe9 cuboctahedra, edges with three equivalent Fe(3)Sm3CrFe8 cuboctahedra, edges with three equivalent Fe(4)Sm3Fe9 cuboctahedra, faces with three equivalent Fe(3)Sm3CrFe8 cuboctahedra, faces with three equivalent Fe(4)Sm3Fe9 cuboctahedra, and faces with four equivalent Fe(2)Sm2CrFe9 cuboctahedra. The Fe(2)-Fe(5) bond length is 2.63 Å. Both Fe(2)-Fe(3) bond lengths are 2.44 Å. Both Fe(2)-Fe(4) bond lengths are 2.46 Å. In the third Fe site, Fe(3) is bonded to one Sm(1), two equivalent Sm(2), one Cr(1), two equivalent Fe(2), two equivalent Fe(4), and four equivalent Fe(1) atoms to form FeSm3CrFe8 cuboctahedra that share corners with two equivalent Fe(3)Sm3CrFe8 cuboctahedra, corners with five equivalent Fe(2)Sm2CrFe9 cuboctahedra, corners with eight equivalent Fe(4)Sm3Fe9 cuboctahedra,  an edgeedge with one Fe(4)Sm3Fe9 cuboctahedra, edges with three equivalent Fe(2)Sm2CrFe9 cuboctahedra, edges with four equivalent Fe(3)Sm3CrFe8 cuboctahedra, faces with three equivalent Fe(2)Sm2CrFe9 cuboctahedra, faces with three equivalent Fe(4)Sm3Fe9 cuboctahedra, and faces with four equivalent Fe(3)Sm3CrFe8 cuboctahedra. Both Fe(3)-Fe(4) bond lengths are 2.48 Å. In the fourth Fe site, Fe(4) is bonded to one Sm(2), two equivalent Sm(1), one Fe(5), two equivalent Fe(2), two equivalent Fe(3), and four equivalent Fe(1) atoms to form FeSm3Fe9 cuboctahedra that share corners with two equivalent Fe(4)Sm3Fe9 cuboctahedra, corners with five equivalent Fe(2)Sm2CrFe9 cuboctahedra, corners with eight equivalent Fe(3)Sm3CrFe8 cuboctahedra,  an edgeedge with one Fe(3)Sm3CrFe8 cuboctahedra, edges with three equivalent Fe(2)Sm2CrFe9 cuboctahedra, edges with four equivalent Fe(4)Sm3Fe9 cuboctahedra, faces with three equivalent Fe(2)Sm2CrFe9 cuboctahedra, faces with three equivalent Fe(3)Sm3CrFe8 cuboctahedra, and faces with four equivalent Fe(4)Sm3Fe9 cuboctahedra. The Fe(4)-Fe(5) bond length is 2.65 Å. In the fifth Fe site, Fe(5) is bonded in a distorted single-bond geometry to one Sm(1), one Cr(1), three equivalent Fe(2), three equivalent Fe(4), and six equivalent Fe(1) atoms.