Tm2Ni17 crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Tm sites. In the first Tm site, Tm(1) is bonded in a 18-coordinate geometry to six equivalent Ni(3) and twelve equivalent Ni(4) atoms. In the second Tm site, Tm(2) is bonded in a 20-coordinate geometry to two equivalent Ni(1), six equivalent Ni(2), six equivalent Ni(3), and six equivalent Ni(4) atoms. There are four inequivalent Ni sites. In the first Ni site, Ni(1) is bonded in a 14-coordinate geometry to one Tm(2), one Ni(1), three equivalent Ni(2), three equivalent Ni(4), and six equivalent Ni(3) atoms. In the second Ni site, Ni(2) is bonded to two equivalent Tm(2), two equivalent Ni(1), four equivalent Ni(3), and four equivalent Ni(4) atoms to form NiTm2Ni10 cuboctahedra that share corners with four equivalent Ni(2)Tm2Ni10 cuboctahedra, corners with ten equivalent Ni(4)Tm3Ni9 cuboctahedra, edges with six equivalent Ni(4)Tm3Ni9 cuboctahedra, faces with four equivalent Ni(4)Tm3Ni9 cuboctahedra, and faces with six equivalent Ni(2)Tm2Ni10 cuboctahedra. In the third Ni site, Ni(3) is bonded in a 12-coordinate geometry to one Tm(1), one Tm(2), two equivalent Ni(1), two equivalent Ni(2), two equivalent Ni(3), and four equivalent Ni(4) atoms. In the fourth Ni site, Ni(4) is bonded to one Tm(2), two equivalent Tm(1), one Ni(1), two equivalent Ni(2), two equivalent Ni(4), and four equivalent Ni(3) atoms to form distorted NiTm3Ni9 cuboctahedra that share corners with five equivalent Ni(2)Tm2Ni10 cuboctahedra, corners with ten equivalent Ni(4)Tm3Ni9 cuboctahedra, edges with three equivalent Ni(2)Tm2Ni10 cuboctahedra, edges with five equivalent Ni(4)Tm3Ni9 cuboctahedra, faces with two equivalent Ni(2)Tm2Ni10 cuboctahedra, and faces with eight equivalent Ni(4)Tm3Ni9 cuboctahedra.
Tm2Ni17 crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Tm sites. In the first Tm site, Tm(1) is bonded in a 18-coordinate geometry to six equivalent Ni(3) and twelve equivalent Ni(4) atoms. All Tm(1)-Ni(3) bond lengths are 2.89 Å. There are six shorter (2.98 Å) and six longer (3.21 Å) Tm(1)-Ni(4) bond lengths. In the second Tm site, Tm(2) is bonded in a 20-coordinate geometry to two equivalent Ni(1), six equivalent Ni(2), six equivalent Ni(3), and six equivalent Ni(4) atoms. Both Tm(2)-Ni(1) bond lengths are 2.80 Å. All Tm(2)-Ni(2) bond lengths are 3.10 Å. All Tm(2)-Ni(3) bond lengths are 2.95 Å. All Tm(2)-Ni(4) bond lengths are 3.01 Å. There are four inequivalent Ni sites. In the first Ni site, Ni(1) is bonded in a 14-coordinate geometry to one Tm(2), one Ni(1), three equivalent Ni(2), three equivalent Ni(4), and six equivalent Ni(3) atoms. The Ni(1)-Ni(1) bond length is 2.38 Å. All Ni(1)-Ni(2) bond lengths are 2.51 Å. All Ni(1)-Ni(4) bond lengths are 2.59 Å. All Ni(1)-Ni(3) bond lengths are 2.70 Å. In the second Ni site, Ni(2) is bonded to two equivalent Tm(2), two equivalent Ni(1), four equivalent Ni(3), and four equivalent Ni(4) atoms to form NiTm2Ni10 cuboctahedra that share corners with four equivalent Ni(2)Tm2Ni10 cuboctahedra, corners with ten equivalent Ni(4)Tm3Ni9 cuboctahedra, edges with six equivalent Ni(4)Tm3Ni9 cuboctahedra, faces with four equivalent Ni(4)Tm3Ni9 cuboctahedra, and faces with six equivalent Ni(2)Tm2Ni10 cuboctahedra. All Ni(2)-Ni(3) bond lengths are 2.37 Å. All Ni(2)-Ni(4) bond lengths are 2.39 Å. In the third Ni site, Ni(3) is bonded in a 12-coordinate geometry to one Tm(1), one Tm(2), two equivalent Ni(1), two equivalent Ni(2), two equivalent Ni(3), and four equivalent Ni(4) atoms. There is one shorter (2.35 Å) and one longer (2.50 Å) Ni(3)-Ni(3) bond length. There are two shorter (2.48 Å) and two longer (2.49 Å) Ni(3)-Ni(4) bond lengths. In the fourth Ni site, Ni(4) is bonded to one Tm(2), two equivalent Tm(1), one Ni(1), two equivalent Ni(2), two equivalent Ni(4), and four equivalent Ni(3) atoms to form distorted NiTm3Ni9 cuboctahedra that share corners with five equivalent Ni(2)Tm2Ni10 cuboctahedra, corners with ten equivalent Ni(4)Tm3Ni9 cuboctahedra, edges with three equivalent Ni(2)Tm2Ni10 cuboctahedra, edges with five equivalent Ni(4)Tm3Ni9 cuboctahedra, faces with two equivalent Ni(2)Tm2Ni10 cuboctahedra, and faces with eight equivalent Ni(4)Tm3Ni9 cuboctahedra. Both Ni(4)-Ni(4) bond lengths are 2.38 Å.