Sm4Co3Ga16 crystallizes in the tetragonal P4/mmm space group. Sm(1) is bonded to two equivalent Ga(1); two equivalent Ga(3); four equivalent Ga(2); and four Ga(4,4,4) atoms to form SmGa12 cuboctahedra that share corners with eight equivalent Sm(1)Ga12 cuboctahedra, edges with two equivalent Ga(3)Sm4Ga8 cuboctahedra, faces with two equivalent Ga(3)Sm4Ga8 cuboctahedra, faces with five equivalent Sm(1)Ga12 cuboctahedra, and faces with two equivalent Co(2)Ga6 octahedra. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded in a body-centered cubic geometry to eight Ga(4,4,4,4,4,4,4) atoms. In the second Co site, Co(2) is bonded to two equivalent Ga(1) and four equivalent Ga(2) atoms to form CoGa6 octahedra that share corners with eight equivalent Ga(3)Sm4Ga8 cuboctahedra and faces with eight equivalent Sm(1)Ga12 cuboctahedra. There are ten inequivalent Ga sites. In the first Ga site, Ga(1) is bonded in a 9-coordinate geometry to four equivalent Sm(1); one Co(2); and four Ga(4,4,4) atoms. In the second Ga site, Ga(2) is bonded in a 9-coordinate geometry to four equivalent Sm(1), one Co(2), two equivalent Ga(2), and two equivalent Ga(3) atoms. In the third Ga site, Ga(3) is bonded to four equivalent Sm(1); four equivalent Ga(2); and four Ga(4,4,4) atoms to form distorted GaSm4Ga8 cuboctahedra that share corners with four equivalent Ga(3)Sm4Ga8 cuboctahedra, corners with four equivalent Co(2)Ga6 octahedra, edges with four equivalent Sm(1)Ga12 cuboctahedra,  a faceface with one Ga(3)Sm4Ga8 cuboctahedra, and faces with four equivalent Sm(1)Ga12 cuboctahedra. The corner-sharing octahedral tilt angles are 49°. In the fourth Ga site, Ga(4) is bonded in a 11-coordinate geometry to two equivalent Sm(1); two equivalent Co(1); one Ga(1); one Ga(3); and five Ga(4,4) atoms. In the fifth Ga site, Ga(4) is bonded in a 11-coordinate geometry to two equivalent Sm(1); two equivalent Co(1); one Ga(1); one Ga(3); and five Ga(4,4,4) atoms. In the sixth Ga site, Ga(4) is bonded in a 11-coordinate geometry to two equivalent Sm(1); two equivalent Co(1); one Ga(1); one Ga(3); and five Ga(4,4) atoms. In the seventh Ga site, Ga(4) is bonded in a 11-coordinate geometry to two equivalent Sm(1); two equivalent Co(1); one Ga(1); one Ga(3); and five Ga(4,4,4) atoms. In the eighth Ga site, Ga(4) is bonded in a 11-coordinate geometry to two equivalent Sm(1); two equivalent Co(1); one Ga(1); one Ga(3); and five Ga(4,4,4) atoms. In the ninth Ga site, Ga(4) is bonded in a 11-coordinate geometry to two equivalent Sm(1); two equivalent Co(1); one Ga(1); one Ga(3); and five Ga(4,4,4) atoms. In the tenth Ga site, Ga(4) is bonded in a 11-coordinate geometry to two equivalent Sm(1); two equivalent Co(1); one Ga(1); one Ga(3); and five Ga(4,4,4) atoms.
Sm4Co3Ga16 crystallizes in the tetragonal P4/mmm space group. Sm(1) is bonded to two equivalent Ga(1); two equivalent Ga(3); four equivalent Ga(2); and four Ga(4,4,4) atoms to form SmGa12 cuboctahedra that share corners with eight equivalent Sm(1)Ga12 cuboctahedra, edges with two equivalent Ga(3)Sm4Ga8 cuboctahedra, faces with two equivalent Ga(3)Sm4Ga8 cuboctahedra, faces with five equivalent Sm(1)Ga12 cuboctahedra, and faces with two equivalent Co(2)Ga6 octahedra. Both Sm(1)-Ga(1) bond lengths are 3.03 Å. Both Sm(1)-Ga(3) bond lengths are 3.01 Å. All Sm(1)-Ga(2) bond lengths are 3.06 Å. All Sm(1)-Ga(4,4,4) bond lengths are 3.01 Å. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded in a body-centered cubic geometry to eight Ga(4,4,4,4,4,4,4) atoms. All Co(1)-Ga(4,4,4,4,4,4,4) bond lengths are 2.48 Å. In the second Co site, Co(2) is bonded to two equivalent Ga(1) and four equivalent Ga(2) atoms to form CoGa6 octahedra that share corners with eight equivalent Ga(3)Sm4Ga8 cuboctahedra and faces with eight equivalent Sm(1)Ga12 cuboctahedra. Both Co(2)-Ga(1) bond lengths are 2.45 Å. All Co(2)-Ga(2) bond lengths are 2.40 Å. There are ten inequivalent Ga sites. In the first Ga site, Ga(1) is bonded in a 9-coordinate geometry to four equivalent Sm(1); one Co(2); and four Ga(4,4,4) atoms. All Ga(1)-Ga(4,4,4) bond lengths are 2.82 Å. In the second Ga site, Ga(2) is bonded in a 9-coordinate geometry to four equivalent Sm(1), one Co(2), two equivalent Ga(2), and two equivalent Ga(3) atoms. Both Ga(2)-Ga(2) bond lengths are 2.64 Å. Both Ga(2)-Ga(3) bond lengths are 2.84 Å. In the third Ga site, Ga(3) is bonded to four equivalent Sm(1); four equivalent Ga(2); and four Ga(4,4,4) atoms to form distorted GaSm4Ga8 cuboctahedra that share corners with four equivalent Ga(3)Sm4Ga8 cuboctahedra, corners with four equivalent Co(2)Ga6 octahedra, edges with four equivalent Sm(1)Ga12 cuboctahedra,  a faceface with one Ga(3)Sm4Ga8 cuboctahedra, and faces with four equivalent Sm(1)Ga12 cuboctahedra. The corner-sharing octahedral tilt angles are 49°. All Ga(3)-Ga(4,4,4) bond lengths are 3.05 Å. In the fourth Ga site, Ga(4) is bonded in a 11-coordinate geometry to two equivalent Sm(1); two equivalent Co(1); one Ga(1); one Ga(3); and five Ga(4,4) atoms. There are a spread of Ga(4)-Ga(4,4) bond distances ranging from 2.52-3.03 Å. In the fifth Ga site, Ga(4) is bonded in a 11-coordinate geometry to two equivalent Sm(1); two equivalent Co(1); one Ga(1); one Ga(3); and five Ga(4,4,4) atoms. Both Ga(4)-Sm(1) bond lengths are 3.01 Å. The Ga(4)-Ga(1) bond length is 2.82 Å. The Ga(4)-Ga(3) bond length is 3.05 Å. There are a spread of Ga(4)-Ga(4,4,4) bond distances ranging from 2.52-3.03 Å. In the sixth Ga site, Ga(4) is bonded in a 11-coordinate geometry to two equivalent Sm(1); two equivalent Co(1); one Ga(1); one Ga(3); and five Ga(4,4) atoms. There are a spread of Ga(4)-Ga(4,4) bond distances ranging from 2.52-3.03 Å. In the seventh Ga site, Ga(4) is bonded in a 11-coordinate geometry to two equivalent Sm(1); two equivalent Co(1); one Ga(1); one Ga(3); and five Ga(4,4,4) atoms. Both Ga(4)-Sm(1) bond lengths are 3.01 Å. The Ga(4)-Ga(1) bond length is 2.82 Å. The Ga(4)-Ga(3) bond length is 3.05 Å. There are a spread of Ga(4)-Ga(4,4,4) bond distances ranging from 2.52-3.03 Å. In the eighth Ga site, Ga(4) is bonded in a 11-coordinate geometry to two equivalent Sm(1); two equivalent Co(1); one Ga(1); one Ga(3); and five Ga(4,4,4) atoms. Both Ga(4)-Sm(1) bond lengths are 3.01 Å. The Ga(4)-Ga(1) bond length is 2.82 Å. The Ga(4)-Ga(3) bond length is 3.05 Å. In the ninth Ga site, Ga(4) is bonded in a 11-coordinate geometry to two equivalent Sm(1); two equivalent Co(1); one Ga(1); one Ga(3); and five Ga(4,4,4) atoms. In the tenth Ga site, Ga(4) is bonded in a 11-coordinate geometry to two equivalent Sm(1); two equivalent Co(1); one Ga(1); one Ga(3); and five Ga(4,4,4) atoms. Both Ga(4)-Sm(1) bond lengths are 3.01 Å. The Ga(4)-Ga(1) bond length is 2.82 Å. The Ga(4)-Ga(3) bond length is 3.05 Å.