Sm2Fe15Si2 crystallizes in the monoclinic Cm 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(2), one Fe(3), one Fe(8), two equivalent Fe(1), two equivalent Fe(10), two equivalent Fe(5), two equivalent Fe(6), two equivalent Fe(7), four equivalent Fe(9), and two equivalent Si(1) atoms. In the second Sm site, Sm(2) is bonded in a 19-coordinate geometry to one Fe(10), one Fe(2), one Fe(4), two equivalent Fe(1), two equivalent Fe(5), two equivalent Fe(6), two equivalent Fe(7), two equivalent Fe(8), two equivalent Fe(9), and four equivalent Si(1) atoms. There are ten inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one Sm(1), one Sm(2), one Fe(10), one Fe(3), one Fe(4), one Fe(5), one Fe(7), one Fe(8), one Fe(9), two equivalent Fe(6), and one Si(1) atom to form distorted FeSm2Fe9Si cuboctahedra that share  a cornercorner with one Fe(10)Sm3Fe7Si2 cuboctahedra,  a cornercorner with one Fe(8)Sm3Fe9 cuboctahedra, corners with two equivalent Fe(2)Sm2Fe8Si2 cuboctahedra, corners with two equivalent Fe(1)Sm2Fe9Si cuboctahedra, corners with four equivalent Fe(9)Sm3Fe8Si cuboctahedra, corners with four equivalent Si(1)Sm3Fe9 cuboctahedra,  an edgeedge with one Fe(10)Sm3Fe7Si2 cuboctahedra,  an edgeedge with one Fe(8)Sm3Fe9 cuboctahedra, edges with two equivalent Fe(9)Sm3Fe8Si cuboctahedra, edges with two equivalent Si(1)Sm3Fe9 cuboctahedra,  a faceface with one Fe(10)Sm3Fe7Si2 cuboctahedra,  a faceface with one Fe(8)Sm3Fe9 cuboctahedra, faces with two equivalent Fe(2)Sm2Fe8Si2 cuboctahedra, faces with two equivalent Fe(1)Sm2Fe9Si cuboctahedra, faces with two equivalent Fe(9)Sm3Fe8Si cuboctahedra, and faces with two equivalent Si(1)Sm3Fe9 cuboctahedra. In the second Fe site, Fe(2) is bonded to one Sm(1), one Sm(2), one Fe(3), one Fe(4), two equivalent Fe(5), two equivalent Fe(7), two equivalent Fe(9), and two equivalent Si(1) atoms to form distorted FeSm2Fe8Si2 cuboctahedra that share corners with two equivalent Fe(9)Sm3Fe8Si cuboctahedra, corners with two equivalent Si(1)Sm3Fe9 cuboctahedra, corners with three equivalent Fe(10)Sm3Fe7Si2 cuboctahedra, corners with three equivalent Fe(8)Sm3Fe9 cuboctahedra, corners with four equivalent Fe(1)Sm2Fe9Si cuboctahedra,  an edgeedge with one Fe(10)Sm3Fe7Si2 cuboctahedra,  an edgeedge with one Fe(8)Sm3Fe9 cuboctahedra, edges with two equivalent Fe(9)Sm3Fe8Si cuboctahedra, edges with two equivalent Si(1)Sm3Fe9 cuboctahedra,  a faceface with one Fe(10)Sm3Fe7Si2 cuboctahedra,  a faceface with one Fe(8)Sm3Fe9 cuboctahedra, faces with two equivalent Fe(9)Sm3Fe8Si cuboctahedra, faces with two equivalent Si(1)Sm3Fe9 cuboctahedra, and faces with four equivalent Fe(1)Sm2Fe9Si cuboctahedra. In the third Fe site, Fe(3) is bonded in a 14-coordinate geometry to one Sm(1), one Fe(10), one Fe(2), one Fe(4), two equivalent Fe(1), two equivalent Fe(5), two equivalent Fe(6), two equivalent Fe(7), and two equivalent Fe(9) atoms. In the fourth Fe site, Fe(4) is bonded in a 14-coordinate geometry to one Sm(2), one Fe(2), one Fe(3), one Fe(8), two equivalent Fe(1), two equivalent Fe(5), two equivalent Fe(6), two equivalent Fe(7), and two equivalent Si(1) atoms. In the fifth Fe site, Fe(5) is bonded in a 12-coordinate geometry to one Sm(1), one Sm(2), one Fe(1), one Fe(2), one Fe(3), one Fe(4), one Fe(5), one Fe(6), one Fe(8), two equivalent Fe(9), and one Si(1) atom. In the sixth Fe site, Fe(6) is bonded in a 12-coordinate geometry to one Sm(1), one Sm(2), one Fe(10), one Fe(3), one Fe(4), one Fe(5), one Fe(7), one Fe(8), one Fe(9), two equivalent Fe(1), and one Si(1) atom. In the seventh Fe site, Fe(7) is bonded in a 12-coordinate geometry to one Sm(1), one Sm(2), one Fe(1), one Fe(10), one Fe(2), one Fe(3), one Fe(4), one Fe(6), one Fe(7), one Fe(9), and two equivalent Si(1) atoms. In the eighth Fe site, Fe(8) is bonded to one Sm(1), two equivalent Sm(2), one Fe(4), two equivalent Fe(1), two equivalent Fe(5), two equivalent Fe(6), and two equivalent Fe(9) atoms to form FeSm3Fe9 cuboctahedra that share corners with two equivalent Fe(1)Sm2Fe9Si cuboctahedra, corners with two equivalent Fe(10)Sm3Fe7Si2 cuboctahedra, corners with two equivalent Fe(8)Sm3Fe9 cuboctahedra, corners with three equivalent Fe(2)Sm2Fe8Si2 cuboctahedra, corners with six equivalent Fe(9)Sm3Fe8Si cuboctahedra,  an edgeedge with one Fe(2)Sm2Fe8Si2 cuboctahedra,  an edgeedge with one Fe(10)Sm3Fe7Si2 cuboctahedra, edges with two equivalent Fe(1)Sm2Fe9Si cuboctahedra, edges with four equivalent Si(1)Sm3Fe9 cuboctahedra,  a faceface with one Fe(2)Sm2Fe8Si2 cuboctahedra,  a faceface with one Fe(10)Sm3Fe7Si2 cuboctahedra, faces with two equivalent Fe(1)Sm2Fe9Si cuboctahedra, faces with two equivalent Fe(9)Sm3Fe8Si cuboctahedra, and faces with four equivalent Si(1)Sm3Fe9 cuboctahedra. In the ninth Fe site, Fe(9) is bonded to one Sm(2), two equivalent Sm(1), one Fe(1), one Fe(2), one Fe(3), one Fe(6), one Fe(7), one Fe(8), two equivalent Fe(5), and one Si(1) atom to form FeSm3Fe8Si cuboctahedra that share  a cornercorner with one Fe(2)Sm2Fe8Si2 cuboctahedra, corners with two equivalent Fe(9)Sm3Fe8Si cuboctahedra, corners with three equivalent Fe(8)Sm3Fe9 cuboctahedra, corners with four equivalent Fe(1)Sm2Fe9Si cuboctahedra, corners with five equivalent Si(1)Sm3Fe9 cuboctahedra,  an edgeedge with one Fe(2)Sm2Fe8Si2 cuboctahedra,  an edgeedge with one Si(1)Sm3Fe9 cuboctahedra, edges with two equivalent Fe(1)Sm2Fe9Si cuboctahedra, edges with two equivalent Fe(10)Sm3Fe7Si2 cuboctahedra, edges with two equivalent Fe(9)Sm3Fe8Si cuboctahedra,  a faceface with one Fe(2)Sm2Fe8Si2 cuboctahedra,  a faceface with one Fe(8)Sm3Fe9 cuboctahedra, faces with two equivalent Fe(1)Sm2Fe9Si cuboctahedra, faces with two equivalent Fe(10)Sm3Fe7Si2 cuboctahedra, faces with two equivalent Fe(9)Sm3Fe8Si cuboctahedra, and faces with two equivalent Si(1)Sm3Fe9 cuboctahedra. In the tenth Fe site, Fe(10) is bonded to one Sm(2), two equivalent Sm(1), one Fe(3), two equivalent Fe(1), two equivalent Fe(6), two equivalent Fe(7), and two equivalent Si(1) atoms to form distorted FeSm3Fe7Si2 cuboctahedra that share corners with two equivalent Fe(1)Sm2Fe9Si cuboctahedra, corners with two equivalent Fe(10)Sm3Fe7Si2 cuboctahedra, corners with two equivalent Fe(8)Sm3Fe9 cuboctahedra, corners with three equivalent Fe(2)Sm2Fe8Si2 cuboctahedra, corners with six equivalent Si(1)Sm3Fe9 cuboctahedra,  an edgeedge with one Fe(2)Sm2Fe8Si2 cuboctahedra,  an edgeedge with one Fe(8)Sm3Fe9 cuboctahedra, edges with two equivalent Fe(1)Sm2Fe9Si cuboctahedra, edges with four equivalent Fe(9)Sm3Fe8Si cuboctahedra,  a faceface with one Fe(2)Sm2Fe8Si2 cuboctahedra,  a faceface with one Fe(8)Sm3Fe9 cuboctahedra, faces with two equivalent Fe(1)Sm2Fe9Si cuboctahedra, faces with two equivalent Si(1)Sm3Fe9 cuboctahedra, and faces with four equivalent Fe(9)Sm3Fe8Si cuboctahedra. Si(1) is bonded to one Sm(1), two equivalent Sm(2), one Fe(1), one Fe(10), one Fe(2), one Fe(4), one Fe(5), one Fe(6), one Fe(9), and two equivalent Fe(7) atoms to form distorted SiSm3Fe9 cuboctahedra that share  a cornercorner with one Fe(2)Sm2Fe8Si2 cuboctahedra, corners with two equivalent Si(1)Sm3Fe9 cuboctahedra, corners with three equivalent Fe(10)Sm3Fe7Si2 cuboctahedra, corners with four equivalent Fe(1)Sm2Fe9Si cuboctahedra, corners with five equivalent Fe(9)Sm3Fe8Si cuboctahedra,  an edgeedge with one Fe(2)Sm2Fe8Si2 cuboctahedra,  an edgeedge with one Fe(9)Sm3Fe8Si cuboctahedra, edges with two equivalent Fe(1)Sm2Fe9Si cuboctahedra, edges with two equivalent Fe(8)Sm3Fe9 cuboctahedra, edges with two equivalent Si(1)Sm3Fe9 cuboctahedra,  a faceface with one Fe(2)Sm2Fe8Si2 cuboctahedra,  a faceface with one Fe(10)Sm3Fe7Si2 cuboctahedra, faces with two equivalent Fe(1)Sm2Fe9Si cuboctahedra, faces with two equivalent Fe(9)Sm3Fe8Si cuboctahedra, faces with two equivalent Fe(8)Sm3Fe9 cuboctahedra, and faces with two equivalent Si(1)Sm3Fe9 cuboctahedra.
Sm2Fe15Si2 crystallizes in the monoclinic Cm 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(2), one Fe(3), one Fe(8), two equivalent Fe(1), two equivalent Fe(10), two equivalent Fe(5), two equivalent Fe(6), two equivalent Fe(7), four equivalent Fe(9), and two equivalent Si(1) atoms. The Sm(1)-Fe(2) bond length is 3.27 Å. The Sm(1)-Fe(3) bond length is 3.01 Å. The Sm(1)-Fe(8) bond length is 3.10 Å. Both Sm(1)-Fe(1) bond lengths are 3.27 Å. There is one shorter (3.17 Å) and one longer (3.26 Å) Sm(1)-Fe(10) bond length. Both Sm(1)-Fe(5) bond lengths are 2.99 Å. Both Sm(1)-Fe(6) bond lengths are 3.00 Å. Both Sm(1)-Fe(7) bond lengths are 3.01 Å. There are two shorter (3.18 Å) and two longer (3.21 Å) Sm(1)-Fe(9) bond lengths. Both Sm(1)-Si(1) bond lengths are 3.13 Å. In the second Sm site, Sm(2) is bonded in a 19-coordinate geometry to one Fe(10), one Fe(2), one Fe(4), two equivalent Fe(1), two equivalent Fe(5), two equivalent Fe(6), two equivalent Fe(7), two equivalent Fe(8), two equivalent Fe(9), and four equivalent Si(1) atoms. The Sm(2)-Fe(10) bond length is 3.07 Å. The Sm(2)-Fe(2) bond length is 3.26 Å. The Sm(2)-Fe(4) bond length is 3.09 Å. Both Sm(2)-Fe(1) bond lengths are 3.26 Å. Both Sm(2)-Fe(5) bond lengths are 3.00 Å. Both Sm(2)-Fe(6) bond lengths are 2.99 Å. Both Sm(2)-Fe(7) bond lengths are 3.00 Å. Both Sm(2)-Fe(8) bond lengths are 3.21 Å. Both Sm(2)-Fe(9) bond lengths are 3.08 Å. There are two shorter (3.19 Å) and two longer (3.21 Å) Sm(2)-Si(1) bond lengths. There are ten inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one Sm(1), one Sm(2), one Fe(10), one Fe(3), one Fe(4), one Fe(5), one Fe(7), one Fe(8), one Fe(9), two equivalent Fe(6), and one Si(1) atom to form distorted FeSm2Fe9Si cuboctahedra that share  a cornercorner with one Fe(10)Sm3Fe7Si2 cuboctahedra,  a cornercorner with one Fe(8)Sm3Fe9 cuboctahedra, corners with two equivalent Fe(2)Sm2Fe8Si2 cuboctahedra, corners with two equivalent Fe(1)Sm2Fe9Si cuboctahedra, corners with four equivalent Fe(9)Sm3Fe8Si cuboctahedra, corners with four equivalent Si(1)Sm3Fe9 cuboctahedra,  an edgeedge with one Fe(10)Sm3Fe7Si2 cuboctahedra,  an edgeedge with one Fe(8)Sm3Fe9 cuboctahedra, edges with two equivalent Fe(9)Sm3Fe8Si cuboctahedra, edges with two equivalent Si(1)Sm3Fe9 cuboctahedra,  a faceface with one Fe(10)Sm3Fe7Si2 cuboctahedra,  a faceface with one Fe(8)Sm3Fe9 cuboctahedra, faces with two equivalent Fe(2)Sm2Fe8Si2 cuboctahedra, faces with two equivalent Fe(1)Sm2Fe9Si cuboctahedra, faces with two equivalent Fe(9)Sm3Fe8Si cuboctahedra, and faces with two equivalent Si(1)Sm3Fe9 cuboctahedra. The Fe(1)-Fe(10) bond length is 2.45 Å. The Fe(1)-Fe(3) bond length is 2.62 Å. The Fe(1)-Fe(4) bond length is 2.58 Å. The Fe(1)-Fe(5) bond length is 2.44 Å. The Fe(1)-Fe(7) bond length is 2.42 Å. The Fe(1)-Fe(8) bond length is 2.42 Å. The Fe(1)-Fe(9) bond length is 2.47 Å. There is one shorter (2.42 Å) and one longer (2.44 Å) Fe(1)-Fe(6) bond length. The Fe(1)-Si(1) bond length is 2.42 Å. In the second Fe site, Fe(2) is bonded to one Sm(1), one Sm(2), one Fe(3), one Fe(4), two equivalent Fe(5), two equivalent Fe(7), two equivalent Fe(9), and two equivalent Si(1) atoms to form distorted FeSm2Fe8Si2 cuboctahedra that share corners with two equivalent Fe(9)Sm3Fe8Si cuboctahedra, corners with two equivalent Si(1)Sm3Fe9 cuboctahedra, corners with three equivalent Fe(10)Sm3Fe7Si2 cuboctahedra, corners with three equivalent Fe(8)Sm3Fe9 cuboctahedra, corners with four equivalent Fe(1)Sm2Fe9Si cuboctahedra,  an edgeedge with one Fe(10)Sm3Fe7Si2 cuboctahedra,  an edgeedge with one Fe(8)Sm3Fe9 cuboctahedra, edges with two equivalent Fe(9)Sm3Fe8Si cuboctahedra, edges with two equivalent Si(1)Sm3Fe9 cuboctahedra,  a faceface with one Fe(10)Sm3Fe7Si2 cuboctahedra,  a faceface with one Fe(8)Sm3Fe9 cuboctahedra, faces with two equivalent Fe(9)Sm3Fe8Si cuboctahedra, faces with two equivalent Si(1)Sm3Fe9 cuboctahedra, and faces with four equivalent Fe(1)Sm2Fe9Si cuboctahedra. The Fe(2)-Fe(3) bond length is 2.63 Å. The Fe(2)-Fe(4) bond length is 2.57 Å. Both Fe(2)-Fe(5) bond lengths are 2.44 Å. Both Fe(2)-Fe(7) bond lengths are 2.45 Å. Both Fe(2)-Fe(9) bond lengths are 2.45 Å. Both Fe(2)-Si(1) bond lengths are 2.41 Å. In the third Fe site, Fe(3) is bonded in a 14-coordinate geometry to one Sm(1), one Fe(10), one Fe(2), one Fe(4), two equivalent Fe(1), two equivalent Fe(5), two equivalent Fe(6), two equivalent Fe(7), and two equivalent Fe(9) atoms. The Fe(3)-Fe(10) bond length is 2.62 Å. The Fe(3)-Fe(4) bond length is 2.36 Å. Both Fe(3)-Fe(5) bond lengths are 2.77 Å. Both Fe(3)-Fe(6) bond lengths are 2.76 Å. Both Fe(3)-Fe(7) bond lengths are 2.77 Å. Both Fe(3)-Fe(9) bond lengths are 2.62 Å. In the fourth Fe site, Fe(4) is bonded in a 14-coordinate geometry to one Sm(2), one Fe(2), one Fe(3), one Fe(8), two equivalent Fe(1), two equivalent Fe(5), two equivalent Fe(6), two equivalent Fe(7), and two equivalent Si(1) atoms. The Fe(4)-Fe(8) bond length is 2.65 Å. Both Fe(4)-Fe(5) bond lengths are 2.78 Å. Both Fe(4)-Fe(6) bond lengths are 2.75 Å. Both Fe(4)-Fe(7) bond lengths are 2.75 Å. Both Fe(4)-Si(1) bond lengths are 2.60 Å. In the fifth Fe site, Fe(5) is bonded in a 12-coordinate geometry to one Sm(1), one Sm(2), one Fe(1), one Fe(2), one Fe(3), one Fe(4), one Fe(5), one Fe(6), one Fe(8), two equivalent Fe(9), and one Si(1) atom. The Fe(5)-Fe(5) bond length is 2.49 Å. The Fe(5)-Fe(6) bond length is 2.51 Å. The Fe(5)-Fe(8) bond length is 2.52 Å. There is one shorter (2.50 Å) and one longer (2.64 Å) Fe(5)-Fe(9) bond length. The Fe(5)-Si(1) bond length is 2.63 Å. In the sixth Fe site, Fe(6) is bonded in a 12-coordinate geometry to one Sm(1), one Sm(2), one Fe(10), one Fe(3), one Fe(4), one Fe(5), one Fe(7), one Fe(8), one Fe(9), two equivalent Fe(1), and one Si(1) atom. The Fe(6)-Fe(10) bond length is 2.62 Å. The Fe(6)-Fe(7) bond length is 2.49 Å. The Fe(6)-Fe(8) bond length is 2.62 Å. The Fe(6)-Fe(9) bond length is 2.52 Å. The Fe(6)-Si(1) bond length is 2.52 Å. In the seventh Fe site, Fe(7) is bonded in a 12-coordinate geometry to one Sm(1), one Sm(2), one Fe(1), one Fe(10), one Fe(2), one Fe(3), one Fe(4), one Fe(6), one Fe(7), one Fe(9), and two equivalent Si(1) atoms. The Fe(7)-Fe(10) bond length is 2.50 Å. The Fe(7)-Fe(7) bond length is 2.49 Å. The Fe(7)-Fe(9) bond length is 2.65 Å. There is one shorter (2.52 Å) and one longer (2.61 Å) Fe(7)-Si(1) bond length. In the eighth Fe site, Fe(8) is bonded to one Sm(1), two equivalent Sm(2), one Fe(4), two equivalent Fe(1), two equivalent Fe(5), two equivalent Fe(6), and two equivalent Fe(9) atoms to form FeSm3Fe9 cuboctahedra that share corners with two equivalent Fe(1)Sm2Fe9Si cuboctahedra, corners with two equivalent Fe(10)Sm3Fe7Si2 cuboctahedra, corners with two equivalent Fe(8)Sm3Fe9 cuboctahedra, corners with three equivalent Fe(2)Sm2Fe8Si2 cuboctahedra, corners with six equivalent Fe(9)Sm3Fe8Si cuboctahedra,  an edgeedge with one Fe(2)Sm2Fe8Si2 cuboctahedra,  an edgeedge with one Fe(10)Sm3Fe7Si2 cuboctahedra, edges with two equivalent Fe(1)Sm2Fe9Si cuboctahedra, edges with four equivalent Si(1)Sm3Fe9 cuboctahedra,  a faceface with one Fe(2)Sm2Fe8Si2 cuboctahedra,  a faceface with one Fe(10)Sm3Fe7Si2 cuboctahedra, faces with two equivalent Fe(1)Sm2Fe9Si cuboctahedra, faces with two equivalent Fe(9)Sm3Fe8Si cuboctahedra, and faces with four equivalent Si(1)Sm3Fe9 cuboctahedra. Both Fe(8)-Fe(9) bond lengths are 2.46 Å. In the ninth Fe site, Fe(9) is bonded to one Sm(2), two equivalent Sm(1), one Fe(1), one Fe(2), one Fe(3), one Fe(6), one Fe(7), one Fe(8), two equivalent Fe(5), and one Si(1) atom to form FeSm3Fe8Si cuboctahedra that share  a cornercorner with one Fe(2)Sm2Fe8Si2 cuboctahedra, corners with two equivalent Fe(9)Sm3Fe8Si cuboctahedra, corners with three equivalent Fe(8)Sm3Fe9 cuboctahedra, corners with four equivalent Fe(1)Sm2Fe9Si cuboctahedra, corners with five equivalent Si(1)Sm3Fe9 cuboctahedra,  an edgeedge with one Fe(2)Sm2Fe8Si2 cuboctahedra,  an edgeedge with one Si(1)Sm3Fe9 cuboctahedra, edges with two equivalent Fe(1)Sm2Fe9Si cuboctahedra, edges with two equivalent Fe(10)Sm3Fe7Si2 cuboctahedra, edges with two equivalent Fe(9)Sm3Fe8Si cuboctahedra,  a faceface with one Fe(2)Sm2Fe8Si2 cuboctahedra,  a faceface with one Fe(8)Sm3Fe9 cuboctahedra, faces with two equivalent Fe(1)Sm2Fe9Si cuboctahedra, faces with two equivalent Fe(10)Sm3Fe7Si2 cuboctahedra, faces with two equivalent Fe(9)Sm3Fe8Si cuboctahedra, and faces with two equivalent Si(1)Sm3Fe9 cuboctahedra. The Fe(9)-Si(1) bond length is 2.46 Å. In the tenth Fe site, Fe(10) is bonded to one Sm(2), two equivalent Sm(1), one Fe(3), two equivalent Fe(1), two equivalent Fe(6), two equivalent Fe(7), and two equivalent Si(1) atoms to form distorted FeSm3Fe7Si2 cuboctahedra that share corners with two equivalent Fe(1)Sm2Fe9Si cuboctahedra, corners with two equivalent Fe(10)Sm3Fe7Si2 cuboctahedra, corners with two equivalent Fe(8)Sm3Fe9 cuboctahedra, corners with three equivalent Fe(2)Sm2Fe8Si2 cuboctahedra, corners with six equivalent Si(1)Sm3Fe9 cuboctahedra,  an edgeedge with one Fe(2)Sm2Fe8Si2 cuboctahedra,  an edgeedge with one Fe(8)Sm3Fe9 cuboctahedra, edges with two equivalent Fe(1)Sm2Fe9Si cuboctahedra, edges with four equivalent Fe(9)Sm3Fe8Si cuboctahedra,  a faceface with one Fe(2)Sm2Fe8Si2 cuboctahedra,  a faceface with one Fe(8)Sm3Fe9 cuboctahedra, faces with two equivalent Fe(1)Sm2Fe9Si cuboctahedra, faces with two equivalent Si(1)Sm3Fe9 cuboctahedra, and faces with four equivalent Fe(9)Sm3Fe8Si cuboctahedra. Both Fe(10)-Si(1) bond lengths are 2.48 Å. Si(1) is bonded to one Sm(1), two equivalent Sm(2), one Fe(1), one Fe(10), one Fe(2), one Fe(4), one Fe(5), one Fe(6), one Fe(9), and two equivalent Fe(7) atoms to form distorted SiSm3Fe9 cuboctahedra that share  a cornercorner with one Fe(2)Sm2Fe8Si2 cuboctahedra, corners with two equivalent Si(1)Sm3Fe9 cuboctahedra, corners with three equivalent Fe(10)Sm3Fe7Si2 cuboctahedra, corners with four equivalent Fe(1)Sm2Fe9Si cuboctahedra, corners with five equivalent Fe(9)Sm3Fe8Si cuboctahedra,  an edgeedge with one Fe(2)Sm2Fe8Si2 cuboctahedra,  an edgeedge with one Fe(9)Sm3Fe8Si cuboctahedra, edges with two equivalent Fe(1)Sm2Fe9Si cuboctahedra, edges with two equivalent Fe(8)Sm3Fe9 cuboctahedra, edges with two equivalent Si(1)Sm3Fe9 cuboctahedra,  a faceface with one Fe(2)Sm2Fe8Si2 cuboctahedra,  a faceface with one Fe(10)Sm3Fe7Si2 cuboctahedra, faces with two equivalent Fe(1)Sm2Fe9Si cuboctahedra, faces with two equivalent Fe(9)Sm3Fe8Si cuboctahedra, faces with two equivalent Fe(8)Sm3Fe9 cuboctahedra, and faces with two equivalent Si(1)Sm3Fe9 cuboctahedra.