Sm2Fe15Co2C3 crystallizes in the monoclinic Cm space group. There are two inequivalent Sm sites. In the first Sm site, Sm(1) is bonded in a distorted trigonal planar geometry to one Fe(5), one Fe(6), two equivalent Fe(4), one C(2), and two equivalent C(1) atoms. In the second Sm site, Sm(2) is bonded in a distorted trigonal planar geometry to one Fe(5), one Fe(7), two equivalent Fe(4), one C(2), and two equivalent C(1) atoms. There are ten inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a single-bond geometry to one Fe(4), one Fe(5), one Fe(6), one Fe(7), and one C(1) atom. In the second Fe site, Fe(2) is bonded in a single-bond geometry to one Fe(6), one Fe(7), two equivalent Fe(4), and one C(2) atom. In the third Fe site, Fe(3) is bonded in a single-bond geometry to one Fe(4), one Fe(5), one Fe(6), one Fe(7), and one C(1) atom. In the fourth Fe site, Fe(4) is bonded to one Sm(1), one Sm(2), one Fe(1), one Fe(10), one Fe(3), one Fe(6), one Fe(7), one Fe(8), one Fe(9), two equivalent Fe(2), and one Co(1) atom to form distorted FeSm2Fe9Co cuboctahedra that share corners with two equivalent Fe(5)Sm2Fe8Co2 cuboctahedra, corners with two equivalent Fe(4)Sm2Fe9Co cuboctahedra, corners with two equivalent C(1)Sm2Fe3Co octahedra, faces with two equivalent Fe(5)Sm2Fe8Co2 cuboctahedra, faces with two equivalent Fe(4)Sm2Fe9Co cuboctahedra, faces with two equivalent C(1)Sm2Fe3Co octahedra, and faces with two equivalent C(2)Sm2Fe4 octahedra. The corner-sharing octahedral tilt angles range from 45-46°. In the fifth Fe site, Fe(5) is bonded to one Sm(1), one Sm(2), one Fe(6), one Fe(7), two equivalent Fe(1), two equivalent Fe(3), two equivalent Fe(9), and two equivalent Co(1) atoms to form distorted FeSm2Fe8Co2 cuboctahedra that share corners with four equivalent Fe(4)Sm2Fe9Co cuboctahedra, corners with two equivalent C(2)Sm2Fe4 octahedra, faces with four equivalent Fe(4)Sm2Fe9Co cuboctahedra, and faces with four equivalent C(1)Sm2Fe3Co octahedra. The corner-sharing octahedral tilt angles are 45°. In the sixth Fe site, Fe(6) is bonded in a 14-coordinate geometry to one Sm(1), one Fe(10), one Fe(5), one Fe(7), two equivalent Fe(1), two equivalent Fe(2), two equivalent Fe(3), two equivalent Fe(4), and two equivalent Fe(9) atoms. In the seventh Fe site, Fe(7) is bonded in a 14-coordinate geometry to one Sm(2), one Fe(5), one Fe(6), one Fe(8), two equivalent Fe(1), two equivalent Fe(2), two equivalent Fe(3), two equivalent Fe(4), and two equivalent Co(1) atoms. In the eighth Fe site, Fe(8) is bonded in a single-bond geometry to one Fe(7), two equivalent Fe(4), and one C(2) atom. In the ninth Fe site, Fe(9) is bonded in a single-bond geometry to one Fe(4), one Fe(5), one Fe(6), and one C(1) atom. In the tenth Fe site, Fe(10) is bonded in a single-bond geometry to one Fe(6), two equivalent Fe(4), and one C(2) atom. Co(1) is bonded in a single-bond geometry to one Fe(4), one Fe(5), one Fe(7), and one C(1) atom. There are two inequivalent C sites. In the first C site, C(1) is bonded to one Sm(1), one Sm(2), one Fe(1), one Fe(3), one Fe(9), and one Co(1) atom to form CSm2Fe3Co octahedra that share corners with two equivalent Fe(4)Sm2Fe9Co cuboctahedra, corners with two equivalent C(1)Sm2Fe3Co octahedra, corners with two equivalent C(2)Sm2Fe4 octahedra, faces with two equivalent Fe(5)Sm2Fe8Co2 cuboctahedra, and faces with two equivalent Fe(4)Sm2Fe9Co cuboctahedra. The corner-sharing octahedral tilt angles range from 60-61°. In the second C site, C(2) is bonded to one Sm(1), one Sm(2), one Fe(10), one Fe(8), and two equivalent Fe(2) atoms to form CSm2Fe4 octahedra that share corners with two equivalent Fe(5)Sm2Fe8Co2 cuboctahedra, corners with four equivalent C(1)Sm2Fe3Co octahedra, and faces with four equivalent Fe(4)Sm2Fe9Co cuboctahedra. The corner-sharing octahedral tilt angles are 60°.
Sm2Fe15Co2C3 crystallizes in the monoclinic Cm space group. There are two inequivalent Sm sites. In the first Sm site, Sm(1) is bonded in a distorted trigonal planar geometry to one Fe(5), one Fe(6), two equivalent Fe(4), one C(2), and two equivalent C(1) atoms. The Sm(1)-Fe(5) bond length is 3.36 Å. The Sm(1)-Fe(6) bond length is 3.12 Å. Both Sm(1)-Fe(4) bond lengths are 3.37 Å. The Sm(1)-C(2) bond length is 2.53 Å. Both Sm(1)-C(1) bond lengths are 2.52 Å. In the second Sm site, Sm(2) is bonded in a distorted trigonal planar geometry to one Fe(5), one Fe(7), two equivalent Fe(4), one C(2), and two equivalent C(1) atoms. The Sm(2)-Fe(5) bond length is 3.36 Å. The Sm(2)-Fe(7) bond length is 3.13 Å. Both Sm(2)-Fe(4) bond lengths are 3.36 Å. The Sm(2)-C(2) bond length is 2.52 Å. Both Sm(2)-C(1) bond lengths are 2.51 Å. There are ten inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a single-bond geometry to one Fe(4), one Fe(5), one Fe(6), one Fe(7), and one C(1) atom. The Fe(1)-Fe(4) bond length is 2.45 Å. The Fe(1)-Fe(5) bond length is 2.45 Å. The Fe(1)-Fe(6) bond length is 2.73 Å. The Fe(1)-Fe(7) bond length is 2.74 Å. The Fe(1)-C(1) bond length is 1.89 Å. In the second Fe site, Fe(2) is bonded in a single-bond geometry to one Fe(6), one Fe(7), two equivalent Fe(4), and one C(2) atom. The Fe(2)-Fe(6) bond length is 2.74 Å. The Fe(2)-Fe(7) bond length is 2.74 Å. There is one shorter (2.44 Å) and one longer (2.45 Å) Fe(2)-Fe(4) bond length. The Fe(2)-C(2) bond length is 1.88 Å. In the third Fe site, Fe(3) is bonded in a single-bond geometry to one Fe(4), one Fe(5), one Fe(6), one Fe(7), and one C(1) atom. The Fe(3)-Fe(4) bond length is 2.44 Å. The Fe(3)-Fe(5) bond length is 2.45 Å. The Fe(3)-Fe(6) bond length is 2.75 Å. The Fe(3)-Fe(7) bond length is 2.73 Å. The Fe(3)-C(1) bond length is 1.89 Å. In the fourth Fe site, Fe(4) is bonded to one Sm(1), one Sm(2), one Fe(1), one Fe(10), one Fe(3), one Fe(6), one Fe(7), one Fe(8), one Fe(9), two equivalent Fe(2), and one Co(1) atom to form distorted FeSm2Fe9Co cuboctahedra that share corners with two equivalent Fe(5)Sm2Fe8Co2 cuboctahedra, corners with two equivalent Fe(4)Sm2Fe9Co cuboctahedra, corners with two equivalent C(1)Sm2Fe3Co octahedra, faces with two equivalent Fe(5)Sm2Fe8Co2 cuboctahedra, faces with two equivalent Fe(4)Sm2Fe9Co cuboctahedra, faces with two equivalent C(1)Sm2Fe3Co octahedra, and faces with two equivalent C(2)Sm2Fe4 octahedra. The corner-sharing octahedral tilt angles range from 45-46°. The Fe(4)-Fe(10) bond length is 2.48 Å. The Fe(4)-Fe(6) bond length is 2.67 Å. The Fe(4)-Fe(7) bond length is 2.66 Å. The Fe(4)-Fe(8) bond length is 2.48 Å. The Fe(4)-Fe(9) bond length is 2.49 Å. The Fe(4)-Co(1) bond length is 2.47 Å. In the fifth Fe site, Fe(5) is bonded to one Sm(1), one Sm(2), one Fe(6), one Fe(7), two equivalent Fe(1), two equivalent Fe(3), two equivalent Fe(9), and two equivalent Co(1) atoms to form distorted FeSm2Fe8Co2 cuboctahedra that share corners with four equivalent Fe(4)Sm2Fe9Co cuboctahedra, corners with two equivalent C(2)Sm2Fe4 octahedra, faces with four equivalent Fe(4)Sm2Fe9Co cuboctahedra, and faces with four equivalent C(1)Sm2Fe3Co octahedra. The corner-sharing octahedral tilt angles are 45°. The Fe(5)-Fe(6) bond length is 2.67 Å. The Fe(5)-Fe(7) bond length is 2.67 Å. Both Fe(5)-Fe(9) bond lengths are 2.49 Å. Both Fe(5)-Co(1) bond lengths are 2.47 Å. In the sixth Fe site, Fe(6) is bonded in a 14-coordinate geometry to one Sm(1), one Fe(10), one Fe(5), one Fe(7), two equivalent Fe(1), two equivalent Fe(2), two equivalent Fe(3), two equivalent Fe(4), and two equivalent Fe(9) atoms. The Fe(6)-Fe(10) bond length is 2.65 Å. The Fe(6)-Fe(7) bond length is 2.37 Å. Both Fe(6)-Fe(9) bond lengths are 2.66 Å. In the seventh Fe site, Fe(7) is bonded in a 14-coordinate geometry to one Sm(2), one Fe(5), one Fe(6), one Fe(8), two equivalent Fe(1), two equivalent Fe(2), two equivalent Fe(3), two equivalent Fe(4), and two equivalent Co(1) atoms. The Fe(7)-Fe(8) bond length is 2.66 Å. Both Fe(7)-Co(1) bond lengths are 2.65 Å. In the eighth Fe site, Fe(8) is bonded in a single-bond geometry to one Fe(7), two equivalent Fe(4), and one C(2) atom. The Fe(8)-C(2) bond length is 1.91 Å. In the ninth Fe site, Fe(9) is bonded in a single-bond geometry to one Fe(4), one Fe(5), one Fe(6), and one C(1) atom. The Fe(9)-C(1) bond length is 1.90 Å. In the tenth Fe site, Fe(10) is bonded in a single-bond geometry to one Fe(6), two equivalent Fe(4), and one C(2) atom. The Fe(10)-C(2) bond length is 1.91 Å. Co(1) is bonded in a single-bond geometry to one Fe(4), one Fe(5), one Fe(7), and one C(1) atom. The Co(1)-C(1) bond length is 1.88 Å. There are two inequivalent C sites. In the first C site, C(1) is bonded to one Sm(1), one Sm(2), one Fe(1), one Fe(3), one Fe(9), and one Co(1) atom to form CSm2Fe3Co octahedra that share corners with two equivalent Fe(4)Sm2Fe9Co cuboctahedra, corners with two equivalent C(1)Sm2Fe3Co octahedra, corners with two equivalent C(2)Sm2Fe4 octahedra, faces with two equivalent Fe(5)Sm2Fe8Co2 cuboctahedra, and faces with two equivalent Fe(4)Sm2Fe9Co cuboctahedra. The corner-sharing octahedral tilt angles range from 60-61°. In the second C site, C(2) is bonded to one Sm(1), one Sm(2), one Fe(10), one Fe(8), and two equivalent Fe(2) atoms to form CSm2Fe4 octahedra that share corners with two equivalent Fe(5)Sm2Fe8Co2 cuboctahedra, corners with four equivalent C(1)Sm2Fe3Co octahedra, and faces with four equivalent Fe(4)Sm2Fe9Co cuboctahedra. The corner-sharing octahedral tilt angles are 60°.