Sm3Cu4Sn4 crystallizes in the orthorhombic Immm space group. There are two inequivalent Sm sites. In the first Sm site, Sm(1) is bonded in a 12-coordinate geometry to six equivalent Cu(1), two equivalent Sn(1), and four equivalent Sn(2) atoms. In the second Sm site, Sm(2) is bonded to two equivalent Sn(1) and four equivalent Sn(2) atoms to form distorted edge-sharing SmSn6 octahedra. Cu(1) is bonded in a 8-coordinate geometry to three equivalent Sm(1), one Cu(1), one Sn(2), and three equivalent Sn(1) atoms. There are two inequivalent Sn sites. In the first Sn site, Sn(1) is bonded in a 9-coordinate geometry to one Sm(2), two equivalent Sm(1), and six equivalent Cu(1) atoms. In the second Sn site, Sn(2) is bonded in a 9-coordinate geometry to two equivalent Sm(2), four equivalent Sm(1), two equivalent Cu(1), and one Sn(2) atom.
Sm3Cu4Sn4 crystallizes in the orthorhombic Immm space group. There are two inequivalent Sm sites. In the first Sm site, Sm(1) is bonded in a 12-coordinate geometry to six equivalent Cu(1), two equivalent Sn(1), and four equivalent Sn(2) atoms. There are four shorter (3.20 Å) and two longer (3.21 Å) Sm(1)-Cu(1) bond lengths. Both Sm(1)-Sn(1) bond lengths are 3.18 Å. All Sm(1)-Sn(2) bond lengths are 3.31 Å. In the second Sm site, Sm(2) is bonded to two equivalent Sn(1) and four equivalent Sn(2) atoms to form distorted edge-sharing SmSn6 octahedra. Both Sm(2)-Sn(1) bond lengths are 3.22 Å. All Sm(2)-Sn(2) bond lengths are 3.07 Å. Cu(1) is bonded in a 8-coordinate geometry to three equivalent Sm(1), one Cu(1), one Sn(2), and three equivalent Sn(1) atoms. The Cu(1)-Cu(1) bond length is 2.57 Å. The Cu(1)-Sn(2) bond length is 2.64 Å. There are two shorter (2.69 Å) and one longer (2.77 Å) Cu(1)-Sn(1) bond length. There are two inequivalent Sn sites. In the first Sn site, Sn(1) is bonded in a 9-coordinate geometry to one Sm(2), two equivalent Sm(1), and six equivalent Cu(1) atoms. In the second Sn site, Sn(2) is bonded in a 9-coordinate geometry to two equivalent Sm(2), four equivalent Sm(1), two equivalent Cu(1), and one Sn(2) atom. The Sn(2)-Sn(2) bond length is 2.80 Å.