Tb2Ni17 crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Tb sites. In the first Tb site, Tb(1) is bonded in a 18-coordinate geometry to six equivalent Ni(2) and twelve equivalent Ni(1) atoms. In the second Tb site, Tb(2) is bonded in a 20-coordinate geometry to two equivalent Ni(3), six equivalent Ni(1), six equivalent Ni(2), and six equivalent Ni(4) atoms. There are four inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one Tb(2), two equivalent Tb(1), one Ni(3), two equivalent Ni(1), two equivalent Ni(4), and four equivalent Ni(2) atoms to form distorted NiTb3Ni9 cuboctahedra that share corners with five equivalent Ni(4)Tb2Ni10 cuboctahedra, corners with ten equivalent Ni(1)Tb3Ni9 cuboctahedra, edges with three equivalent Ni(4)Tb2Ni10 cuboctahedra, edges with five equivalent Ni(1)Tb3Ni9 cuboctahedra, faces with two equivalent Ni(4)Tb2Ni10 cuboctahedra, and faces with eight equivalent Ni(1)Tb3Ni9 cuboctahedra. In the second Ni site, Ni(2) is bonded in a 12-coordinate geometry to one Tb(1), one Tb(2), two equivalent Ni(2), two equivalent Ni(3), two equivalent Ni(4), and four equivalent Ni(1) atoms. In the third Ni site, Ni(3) is bonded in a 14-coordinate geometry to one Tb(2), one Ni(3), three equivalent Ni(1), three equivalent Ni(4), and six equivalent Ni(2) atoms. In the fourth Ni site, Ni(4) is bonded to two equivalent Tb(2), two equivalent Ni(3), four equivalent Ni(1), and four equivalent Ni(2) atoms to form NiTb2Ni10 cuboctahedra that share corners with four equivalent Ni(4)Tb2Ni10 cuboctahedra, corners with ten equivalent Ni(1)Tb3Ni9 cuboctahedra, edges with six equivalent Ni(1)Tb3Ni9 cuboctahedra, faces with four equivalent Ni(1)Tb3Ni9 cuboctahedra, and faces with six equivalent Ni(4)Tb2Ni10 cuboctahedra.
Tb2Ni17 crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Tb sites. In the first Tb site, Tb(1) is bonded in a 18-coordinate geometry to six equivalent Ni(2) and twelve equivalent Ni(1) atoms. All Tb(1)-Ni(2) bond lengths are 2.91 Å. There are six shorter (3.00 Å) and six longer (3.21 Å) Tb(1)-Ni(1) bond lengths. In the second Tb site, Tb(2) is bonded in a 20-coordinate geometry to two equivalent Ni(3), six equivalent Ni(1), six equivalent Ni(2), and six equivalent Ni(4) atoms. Both Tb(2)-Ni(3) bond lengths are 2.82 Å. All Tb(2)-Ni(1) bond lengths are 3.02 Å. All Tb(2)-Ni(2) bond lengths are 2.97 Å. All Tb(2)-Ni(4) bond lengths are 3.12 Å. There are four inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one Tb(2), two equivalent Tb(1), one Ni(3), two equivalent Ni(1), two equivalent Ni(4), and four equivalent Ni(2) atoms to form distorted NiTb3Ni9 cuboctahedra that share corners with five equivalent Ni(4)Tb2Ni10 cuboctahedra, corners with ten equivalent Ni(1)Tb3Ni9 cuboctahedra, edges with three equivalent Ni(4)Tb2Ni10 cuboctahedra, edges with five equivalent Ni(1)Tb3Ni9 cuboctahedra, faces with two equivalent Ni(4)Tb2Ni10 cuboctahedra, and faces with eight equivalent Ni(1)Tb3Ni9 cuboctahedra. The Ni(1)-Ni(3) bond length is 2.60 Å. Both Ni(1)-Ni(1) bond lengths are 2.40 Å. Both Ni(1)-Ni(4) bond lengths are 2.40 Å. There are two shorter (2.48 Å) and two longer (2.51 Å) Ni(1)-Ni(2) bond lengths. In the second Ni site, Ni(2) is bonded in a 12-coordinate geometry to one Tb(1), one Tb(2), two equivalent Ni(2), two equivalent Ni(3), two equivalent Ni(4), and four equivalent Ni(1) atoms. There is one shorter (2.36 Å) and one longer (2.49 Å) Ni(2)-Ni(2) bond length. Both Ni(2)-Ni(3) bond lengths are 2.70 Å. Both Ni(2)-Ni(4) bond lengths are 2.38 Å. In the third Ni site, Ni(3) is bonded in a 14-coordinate geometry to one Tb(2), one Ni(3), three equivalent Ni(1), three equivalent Ni(4), and six equivalent Ni(2) atoms. The Ni(3)-Ni(3) bond length is 2.37 Å. All Ni(3)-Ni(4) bond lengths are 2.52 Å. In the fourth Ni site, Ni(4) is bonded to two equivalent Tb(2), two equivalent Ni(3), four equivalent Ni(1), and four equivalent Ni(2) atoms to form NiTb2Ni10 cuboctahedra that share corners with four equivalent Ni(4)Tb2Ni10 cuboctahedra, corners with ten equivalent Ni(1)Tb3Ni9 cuboctahedra, edges with six equivalent Ni(1)Tb3Ni9 cuboctahedra, faces with four equivalent Ni(1)Tb3Ni9 cuboctahedra, and faces with six equivalent Ni(4)Tb2Ni10 cuboctahedra.