Th2Zn17 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 Zn(3) and twelve equivalent Zn(4) atoms. In the second Th site, Th(2) is bonded in a 20-coordinate geometry to two equivalent Zn(1), six equivalent Zn(2), six equivalent Zn(3), and six equivalent Zn(4) atoms. There are four inequivalent Zn sites. In the first Zn site, Zn(1) is bonded in a 14-coordinate geometry to one Th(2), one Zn(1), three equivalent Zn(2), three equivalent Zn(4), and six equivalent Zn(3) atoms. In the second Zn site, Zn(2) is bonded to two equivalent Th(2), two equivalent Zn(1), four equivalent Zn(3), and four equivalent Zn(4) atoms to form ZnTh2Zn10 cuboctahedra that share corners with four equivalent Zn(2)Th2Zn10 cuboctahedra, corners with eight equivalent Zn(3)Th2Zn10 cuboctahedra, corners with ten equivalent Zn(4)Th3Zn9 cuboctahedra, edges with four equivalent Zn(3)Th2Zn10 cuboctahedra, edges with six equivalent Zn(4)Th3Zn9 cuboctahedra, faces with four equivalent Zn(4)Th3Zn9 cuboctahedra, faces with six equivalent Zn(2)Th2Zn10 cuboctahedra, and faces with eight equivalent Zn(3)Th2Zn10 cuboctahedra. In the third Zn site, Zn(3) is bonded to one Th(1), one Th(2), two equivalent Zn(1), two equivalent Zn(2), two equivalent Zn(3), and four equivalent Zn(4) atoms to form distorted ZnTh2Zn10 cuboctahedra that share corners with four equivalent Zn(2)Th2Zn10 cuboctahedra, corners with eight equivalent Zn(4)Th3Zn9 cuboctahedra, corners with twelve equivalent Zn(3)Th2Zn10 cuboctahedra,  an edgeedge with one Zn(3)Th2Zn10 cuboctahedra, edges with two equivalent Zn(2)Th2Zn10 cuboctahedra, edges with two equivalent Zn(4)Th3Zn9 cuboctahedra, faces with four equivalent Zn(2)Th2Zn10 cuboctahedra, faces with seven equivalent Zn(3)Th2Zn10 cuboctahedra, and faces with ten equivalent Zn(4)Th3Zn9 cuboctahedra. In the fourth Zn site, Zn(4) is bonded to one Th(2), two equivalent Th(1), one Zn(1), two equivalent Zn(2), two equivalent Zn(4), and four equivalent Zn(3) atoms to form distorted ZnTh3Zn9 cuboctahedra that share corners with five equivalent Zn(2)Th2Zn10 cuboctahedra, corners with eight equivalent Zn(3)Th2Zn10 cuboctahedra, corners with ten equivalent Zn(4)Th3Zn9 cuboctahedra, edges with two equivalent Zn(3)Th2Zn10 cuboctahedra, edges with three equivalent Zn(2)Th2Zn10 cuboctahedra, edges with five equivalent Zn(4)Th3Zn9 cuboctahedra, faces with two equivalent Zn(2)Th2Zn10 cuboctahedra, faces with eight equivalent Zn(4)Th3Zn9 cuboctahedra, and faces with ten equivalent Zn(3)Th2Zn10 cuboctahedra.
Th2Zn17 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 Zn(3) and twelve equivalent Zn(4) atoms. All Th(1)-Zn(3) bond lengths are 3.17 Å. There are six shorter (3.23 Å) and six longer (3.46 Å) Th(1)-Zn(4) bond lengths. In the second Th site, Th(2) is bonded in a 20-coordinate geometry to two equivalent Zn(1), six equivalent Zn(2), six equivalent Zn(3), and six equivalent Zn(4) atoms. Both Th(2)-Zn(1) bond lengths are 3.10 Å. All Th(2)-Zn(2) bond lengths are 3.39 Å. All Th(2)-Zn(3) bond lengths are 3.22 Å. All Th(2)-Zn(4) bond lengths are 3.32 Å. There are four inequivalent Zn sites. In the first Zn site, Zn(1) is bonded in a 14-coordinate geometry to one Th(2), one Zn(1), three equivalent Zn(2), three equivalent Zn(4), and six equivalent Zn(3) atoms. The Zn(1)-Zn(1) bond length is 2.56 Å. All Zn(1)-Zn(2) bond lengths are 2.74 Å. All Zn(1)-Zn(4) bond lengths are 2.86 Å. All Zn(1)-Zn(3) bond lengths are 2.90 Å. In the second Zn site, Zn(2) is bonded to two equivalent Th(2), two equivalent Zn(1), four equivalent Zn(3), and four equivalent Zn(4) atoms to form ZnTh2Zn10 cuboctahedra that share corners with four equivalent Zn(2)Th2Zn10 cuboctahedra, corners with eight equivalent Zn(3)Th2Zn10 cuboctahedra, corners with ten equivalent Zn(4)Th3Zn9 cuboctahedra, edges with four equivalent Zn(3)Th2Zn10 cuboctahedra, edges with six equivalent Zn(4)Th3Zn9 cuboctahedra, faces with four equivalent Zn(4)Th3Zn9 cuboctahedra, faces with six equivalent Zn(2)Th2Zn10 cuboctahedra, and faces with eight equivalent Zn(3)Th2Zn10 cuboctahedra. All Zn(2)-Zn(3) bond lengths are 2.58 Å. All Zn(2)-Zn(4) bond lengths are 2.62 Å. In the third Zn site, Zn(3) is bonded to one Th(1), one Th(2), two equivalent Zn(1), two equivalent Zn(2), two equivalent Zn(3), and four equivalent Zn(4) atoms to form distorted ZnTh2Zn10 cuboctahedra that share corners with four equivalent Zn(2)Th2Zn10 cuboctahedra, corners with eight equivalent Zn(4)Th3Zn9 cuboctahedra, corners with twelve equivalent Zn(3)Th2Zn10 cuboctahedra,  an edgeedge with one Zn(3)Th2Zn10 cuboctahedra, edges with two equivalent Zn(2)Th2Zn10 cuboctahedra, edges with two equivalent Zn(4)Th3Zn9 cuboctahedra, faces with four equivalent Zn(2)Th2Zn10 cuboctahedra, faces with seven equivalent Zn(3)Th2Zn10 cuboctahedra, and faces with ten equivalent Zn(4)Th3Zn9 cuboctahedra. There is one shorter (2.56 Å) and one longer (2.65 Å) Zn(3)-Zn(3) bond length. There are two shorter (2.71 Å) and two longer (2.75 Å) Zn(3)-Zn(4) bond lengths. In the fourth Zn site, Zn(4) is bonded to one Th(2), two equivalent Th(1), one Zn(1), two equivalent Zn(2), two equivalent Zn(4), and four equivalent Zn(3) atoms to form distorted ZnTh3Zn9 cuboctahedra that share corners with five equivalent Zn(2)Th2Zn10 cuboctahedra, corners with eight equivalent Zn(3)Th2Zn10 cuboctahedra, corners with ten equivalent Zn(4)Th3Zn9 cuboctahedra, edges with two equivalent Zn(3)Th2Zn10 cuboctahedra, edges with three equivalent Zn(2)Th2Zn10 cuboctahedra, edges with five equivalent Zn(4)Th3Zn9 cuboctahedra, faces with two equivalent Zn(2)Th2Zn10 cuboctahedra, faces with eight equivalent Zn(4)Th3Zn9 cuboctahedra, and faces with ten equivalent Zn(3)Th2Zn10 cuboctahedra. Both Zn(4)-Zn(4) bond lengths are 2.55 Å.