Tm3Co6Sn5 crystallizes in the orthorhombic Immm space group. There are two inequivalent Tm sites. In the first Tm site, Tm(1) is bonded to four equivalent Co(2) and eight equivalent Sn(1) atoms to form distorted TmCo4Sn8 cuboctahedra that share edges with two equivalent Sn(2)Tm4Co8 cuboctahedra and faces with two equivalent Tm(1)Co4Sn8 cuboctahedra. In the second Tm site, Tm(2) is bonded in a 14-coordinate geometry to two equivalent Co(1), four equivalent Co(2), two equivalent Sn(2), and six equivalent Sn(1) atoms. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded in a 10-coordinate geometry to two equivalent Tm(2), four equivalent Co(2), two equivalent Sn(1), and two equivalent Sn(2) atoms. In the second Co site, Co(2) is bonded in a 10-coordinate geometry to one Tm(1), two equivalent Tm(2), one Co(2), two equivalent Co(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 10-coordinate geometry to two equivalent Tm(1), three equivalent Tm(2), one Co(1), three equivalent Co(2), and one Sn(1) atom. In the second Sn site, Sn(2) is bonded to four equivalent Tm(2), four equivalent Co(1), and four equivalent Co(2) atoms to form SnTm4Co8 cuboctahedra that share edges with two equivalent Tm(1)Co4Sn8 cuboctahedra and faces with two equivalent Sn(2)Tm4Co8 cuboctahedra.
Tm3Co6Sn5 crystallizes in the orthorhombic Immm space group. There are two inequivalent Tm sites. In the first Tm site, Tm(1) is bonded to four equivalent Co(2) and eight equivalent Sn(1) atoms to form distorted TmCo4Sn8 cuboctahedra that share edges with two equivalent Sn(2)Tm4Co8 cuboctahedra and faces with two equivalent Tm(1)Co4Sn8 cuboctahedra. All Tm(1)-Co(2) bond lengths are 2.93 Å. All Tm(1)-Sn(1) bond lengths are 3.40 Å. In the second Tm site, Tm(2) is bonded in a 14-coordinate geometry to two equivalent Co(1), four equivalent Co(2), two equivalent Sn(2), and six equivalent Sn(1) atoms. Both Tm(2)-Co(1) bond lengths are 2.92 Å. All Tm(2)-Co(2) bond lengths are 3.19 Å. Both Tm(2)-Sn(2) bond lengths are 3.11 Å. There are four shorter (3.13 Å) and two longer (3.27 Å) Tm(2)-Sn(1) bond lengths. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded in a 10-coordinate geometry to two equivalent Tm(2), four equivalent Co(2), two equivalent Sn(1), and two equivalent Sn(2) atoms. All Co(1)-Co(2) bond lengths are 2.54 Å. Both Co(1)-Sn(1) bond lengths are 2.58 Å. Both Co(1)-Sn(2) bond lengths are 2.85 Å. In the second Co site, Co(2) is bonded in a 10-coordinate geometry to one Tm(1), two equivalent Tm(2), one Co(2), two equivalent Co(1), one Sn(2), and three equivalent Sn(1) atoms. The Co(2)-Co(2) bond length is 2.65 Å. The Co(2)-Sn(2) bond length is 2.54 Å. There are two shorter (2.56 Å) and one longer (2.72 Å) Co(2)-Sn(1) bond length. There are two inequivalent Sn sites. In the first Sn site, Sn(1) is bonded in a 10-coordinate geometry to two equivalent Tm(1), three equivalent Tm(2), one Co(1), three equivalent Co(2), and one Sn(1) atom. The Sn(1)-Sn(1) bond length is 3.01 Å. In the second Sn site, Sn(2) is bonded to four equivalent Tm(2), four equivalent Co(1), and four equivalent Co(2) atoms to form SnTm4Co8 cuboctahedra that share edges with two equivalent Tm(1)Co4Sn8 cuboctahedra and faces with two equivalent Sn(2)Tm4Co8 cuboctahedra.