Th2Ni17 crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Th sites. In the first Th site, Th(1) is bonded in a 18-coordinate geometry to six equivalent Ni(3) and twelve equivalent Ni(4) atoms. In the second Th site, Th(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 Th(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 Th(2), two equivalent Ni(1), four equivalent Ni(3), and four equivalent Ni(4) atoms to form NiTh2Ni10 cuboctahedra that share corners with four equivalent Ni(2)Th2Ni10 cuboctahedra, corners with eight equivalent Ni(3)Th2Ni10 cuboctahedra, corners with ten equivalent Ni(4)Th3Ni9 cuboctahedra, edges with four equivalent Ni(3)Th2Ni10 cuboctahedra, edges with six equivalent Ni(4)Th3Ni9 cuboctahedra, faces with four equivalent Ni(4)Th3Ni9 cuboctahedra, faces with six equivalent Ni(2)Th2Ni10 cuboctahedra, and faces with eight equivalent Ni(3)Th2Ni10 cuboctahedra. In the third Ni site, Ni(3) is bonded to one Th(1), one Th(2), two equivalent Ni(1), two equivalent Ni(2), two equivalent Ni(3), and four equivalent Ni(4) atoms to form distorted NiTh2Ni10 cuboctahedra that share corners with four equivalent Ni(2)Th2Ni10 cuboctahedra, corners with eight equivalent Ni(4)Th3Ni9 cuboctahedra, corners with twelve equivalent Ni(3)Th2Ni10 cuboctahedra,  an edgeedge with one Ni(3)Th2Ni10 cuboctahedra, edges with two equivalent Ni(2)Th2Ni10 cuboctahedra, edges with two equivalent Ni(4)Th3Ni9 cuboctahedra, faces with four equivalent Ni(2)Th2Ni10 cuboctahedra, faces with seven equivalent Ni(3)Th2Ni10 cuboctahedra, and faces with ten equivalent Ni(4)Th3Ni9 cuboctahedra. In the fourth Ni site, Ni(4) is bonded to one Th(2), two equivalent Th(1), one Ni(1), two equivalent Ni(2), two equivalent Ni(4), and four equivalent Ni(3) atoms to form distorted NiTh3Ni9 cuboctahedra that share corners with five equivalent Ni(2)Th2Ni10 cuboctahedra, corners with eight equivalent Ni(3)Th2Ni10 cuboctahedra, corners with ten equivalent Ni(4)Th3Ni9 cuboctahedra, edges with two equivalent Ni(3)Th2Ni10 cuboctahedra, edges with three equivalent Ni(2)Th2Ni10 cuboctahedra, edges with five equivalent Ni(4)Th3Ni9 cuboctahedra, faces with two equivalent Ni(2)Th2Ni10 cuboctahedra, faces with eight equivalent Ni(4)Th3Ni9 cuboctahedra, and faces with ten equivalent Ni(3)Th2Ni10 cuboctahedra.
Th2Ni17 crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Th sites. In the first Th site, Th(1) is bonded in a 18-coordinate geometry to six equivalent Ni(3) and twelve equivalent Ni(4) atoms. All Th(1)-Ni(3) bond lengths are 2.93 Å. There are six shorter (3.01 Å) and six longer (3.21 Å) Th(1)-Ni(4) bond lengths. In the second Th site, Th(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 Th(2)-Ni(1) bond lengths are 2.82 Å. All Th(2)-Ni(2) bond lengths are 3.12 Å. All Th(2)-Ni(3) bond lengths are 2.99 Å. All Th(2)-Ni(4) bond lengths are 3.03 Å. There are four inequivalent Ni sites. In the first Ni site, Ni(1) is bonded in a 14-coordinate geometry to one Th(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 2.35 Å. All Ni(1)-Ni(2) bond lengths are 2.53 Å. All Ni(1)-Ni(4) bond lengths are 2.60 Å. All Ni(1)-Ni(3) bond lengths are 2.68 Å. In the second Ni site, Ni(2) is bonded to two equivalent Th(2), two equivalent Ni(1), four equivalent Ni(3), and four equivalent Ni(4) atoms to form NiTh2Ni10 cuboctahedra that share corners with four equivalent Ni(2)Th2Ni10 cuboctahedra, corners with eight equivalent Ni(3)Th2Ni10 cuboctahedra, corners with ten equivalent Ni(4)Th3Ni9 cuboctahedra, edges with four equivalent Ni(3)Th2Ni10 cuboctahedra, edges with six equivalent Ni(4)Th3Ni9 cuboctahedra, faces with four equivalent Ni(4)Th3Ni9 cuboctahedra, faces with six equivalent Ni(2)Th2Ni10 cuboctahedra, and faces with eight equivalent Ni(3)Th2Ni10 cuboctahedra. All Ni(2)-Ni(3) bond lengths are 2.37 Å. All Ni(2)-Ni(4) bond lengths are 2.40 Å. In the third Ni site, Ni(3) is bonded to one Th(1), one Th(2), two equivalent Ni(1), two equivalent Ni(2), two equivalent Ni(3), and four equivalent Ni(4) atoms to form distorted NiTh2Ni10 cuboctahedra that share corners with four equivalent Ni(2)Th2Ni10 cuboctahedra, corners with eight equivalent Ni(4)Th3Ni9 cuboctahedra, corners with twelve equivalent Ni(3)Th2Ni10 cuboctahedra,  an edgeedge with one Ni(3)Th2Ni10 cuboctahedra, edges with two equivalent Ni(2)Th2Ni10 cuboctahedra, edges with two equivalent Ni(4)Th3Ni9 cuboctahedra, faces with four equivalent Ni(2)Th2Ni10 cuboctahedra, faces with seven equivalent Ni(3)Th2Ni10 cuboctahedra, and faces with ten equivalent Ni(4)Th3Ni9 cuboctahedra. There is one shorter (2.34 Å) and one longer (2.47 Å) Ni(3)-Ni(3) bond length. There are two shorter (2.47 Å) and two longer (2.54 Å) Ni(3)-Ni(4) bond lengths. In the fourth Ni site, Ni(4) is bonded to one Th(2), two equivalent Th(1), one Ni(1), two equivalent Ni(2), two equivalent Ni(4), and four equivalent Ni(3) atoms to form distorted NiTh3Ni9 cuboctahedra that share corners with five equivalent Ni(2)Th2Ni10 cuboctahedra, corners with eight equivalent Ni(3)Th2Ni10 cuboctahedra, corners with ten equivalent Ni(4)Th3Ni9 cuboctahedra, edges with two equivalent Ni(3)Th2Ni10 cuboctahedra, edges with three equivalent Ni(2)Th2Ni10 cuboctahedra, edges with five equivalent Ni(4)Th3Ni9 cuboctahedra, faces with two equivalent Ni(2)Th2Ni10 cuboctahedra, faces with eight equivalent Ni(4)Th3Ni9 cuboctahedra, and faces with ten equivalent Ni(3)Th2Ni10 cuboctahedra. Both Ni(4)-Ni(4) bond lengths are 2.40 Å.