Sm2TiCo16 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 Co(5), three equivalent Co(2), three equivalent Co(3), six equivalent Co(1), and six equivalent Co(4) atoms. In the second Sm site, Sm(2) is bonded in a 19-coordinate geometry to one Ti(1), three equivalent Co(2), three equivalent Co(4), six equivalent Co(1), and six equivalent Co(3) atoms. Ti(1) is bonded in a 14-coordinate geometry to one Sm(2), one Co(5), three equivalent Co(2), three equivalent Co(3), and six equivalent Co(1) atoms. There are five inequivalent Co sites. In the first Co site, Co(1) is bonded in a 12-coordinate geometry to one Sm(1), one Sm(2), one Ti(1), one Co(5), two equivalent Co(1), two equivalent Co(2), two equivalent Co(3), and two equivalent Co(4) atoms. In the second Co site, Co(2) is bonded in a 12-coordinate geometry to one Sm(1), one Sm(2), one Ti(1), one Co(5), two equivalent Co(3), two equivalent Co(4), and four equivalent Co(1) atoms. In the third Co site, Co(3) is bonded to one Sm(1), two equivalent Sm(2), one Ti(1), two equivalent Co(2), two equivalent Co(4), and four equivalent Co(1) atoms to form distorted CoSm3TiCo8 cuboctahedra that share corners with two equivalent Co(3)Sm3TiCo8 cuboctahedra, corners with eight equivalent Co(4)Sm3Co9 cuboctahedra,  an edgeedge with one Co(4)Sm3Co9 cuboctahedra, edges with four equivalent Co(3)Sm3TiCo8 cuboctahedra, faces with three equivalent Co(4)Sm3Co9 cuboctahedra, and faces with four equivalent Co(3)Sm3TiCo8 cuboctahedra. In the fourth Co site, Co(4) is bonded to one Sm(2), two equivalent Sm(1), one Co(5), two equivalent Co(2), two equivalent Co(3), and four equivalent Co(1) atoms to form CoSm3Co9 cuboctahedra that share corners with two equivalent Co(4)Sm3Co9 cuboctahedra, corners with eight equivalent Co(3)Sm3TiCo8 cuboctahedra,  an edgeedge with one Co(3)Sm3TiCo8 cuboctahedra, edges with four equivalent Co(4)Sm3Co9 cuboctahedra, faces with three equivalent Co(3)Sm3TiCo8 cuboctahedra, and faces with four equivalent Co(4)Sm3Co9 cuboctahedra. In the fifth Co site, Co(5) is bonded in a 1-coordinate geometry to one Sm(1), one Ti(1), three equivalent Co(2), three equivalent Co(4), and six equivalent Co(1) atoms.
Sm2TiCo16 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 Co(5), three equivalent Co(2), three equivalent Co(3), six equivalent Co(1), and six equivalent Co(4) atoms. The Sm(1)-Co(5) bond length is 2.98 Å. All Sm(1)-Co(2) bond lengths are 3.22 Å. All Sm(1)-Co(3) bond lengths are 2.99 Å. All Sm(1)-Co(1) bond lengths are 2.98 Å. There are three shorter (3.15 Å) and three longer (3.17 Å) Sm(1)-Co(4) bond lengths. In the second Sm site, Sm(2) is bonded in a 19-coordinate geometry to one Ti(1), three equivalent Co(2), three equivalent Co(4), six equivalent Co(1), and six equivalent Co(3) atoms. The Sm(2)-Ti(1) bond length is 3.17 Å. All Sm(2)-Co(2) bond lengths are 3.34 Å. All Sm(2)-Co(4) bond lengths are 2.99 Å. All Sm(2)-Co(1) bond lengths are 3.00 Å. There are three shorter (3.11 Å) and three longer (3.21 Å) Sm(2)-Co(3) bond lengths. Ti(1) is bonded in a 14-coordinate geometry to one Sm(2), one Co(5), three equivalent Co(2), three equivalent Co(3), and six equivalent Co(1) atoms. The Ti(1)-Co(5) bond length is 2.37 Å. All Ti(1)-Co(2) bond lengths are 2.61 Å. All Ti(1)-Co(3) bond lengths are 2.62 Å. All Ti(1)-Co(1) bond lengths are 2.69 Å. There are five inequivalent Co sites. In the first Co site, Co(1) is bonded in a 12-coordinate geometry to one Sm(1), one Sm(2), one Ti(1), one Co(5), two equivalent Co(1), two equivalent Co(2), two equivalent Co(3), and two equivalent Co(4) atoms. The Co(1)-Co(5) bond length is 2.72 Å. There is one shorter (2.42 Å) and one longer (2.44 Å) Co(1)-Co(1) bond length. There is one shorter (2.38 Å) and one longer (2.41 Å) Co(1)-Co(2) bond length. There is one shorter (2.54 Å) and one longer (2.56 Å) Co(1)-Co(3) bond length. There is one shorter (2.45 Å) and one longer (2.63 Å) Co(1)-Co(4) bond length. In the second Co site, Co(2) is bonded in a 12-coordinate geometry to one Sm(1), one Sm(2), one Ti(1), one Co(5), two equivalent Co(3), two equivalent Co(4), and four equivalent Co(1) atoms. The Co(2)-Co(5) bond length is 2.51 Å. Both Co(2)-Co(3) bond lengths are 2.43 Å. Both Co(2)-Co(4) bond lengths are 2.38 Å. In the third Co site, Co(3) is bonded to one Sm(1), two equivalent Sm(2), one Ti(1), two equivalent Co(2), two equivalent Co(4), and four equivalent Co(1) atoms to form distorted CoSm3TiCo8 cuboctahedra that share corners with two equivalent Co(3)Sm3TiCo8 cuboctahedra, corners with eight equivalent Co(4)Sm3Co9 cuboctahedra,  an edgeedge with one Co(4)Sm3Co9 cuboctahedra, edges with four equivalent Co(3)Sm3TiCo8 cuboctahedra, faces with three equivalent Co(4)Sm3Co9 cuboctahedra, and faces with four equivalent Co(3)Sm3TiCo8 cuboctahedra. Both Co(3)-Co(4) bond lengths are 2.46 Å. In the fourth Co site, Co(4) is bonded to one Sm(2), two equivalent Sm(1), one Co(5), two equivalent Co(2), two equivalent Co(3), and four equivalent Co(1) atoms to form CoSm3Co9 cuboctahedra that share corners with two equivalent Co(4)Sm3Co9 cuboctahedra, corners with eight equivalent Co(3)Sm3TiCo8 cuboctahedra,  an edgeedge with one Co(3)Sm3TiCo8 cuboctahedra, edges with four equivalent Co(4)Sm3Co9 cuboctahedra, faces with three equivalent Co(3)Sm3TiCo8 cuboctahedra, and faces with four equivalent Co(4)Sm3Co9 cuboctahedra. The Co(4)-Co(5) bond length is 2.53 Å. In the fifth Co site, Co(5) is bonded in a 1-coordinate geometry to one Sm(1), one Ti(1), three equivalent Co(2), three equivalent Co(4), and six equivalent Co(1) atoms.