U8ThO18 is Fluorite-derived structured and crystallizes in the triclinic P-1 space group. There are four inequivalent U sites. In the first U site, U(1) is bonded in a body-centered cubic geometry to one O(2), one O(3), one O(4), one O(5), one O(7), one O(9), and two equivalent O(1) atoms. In the second U site, U(2) is bonded in a body-centered cubic geometry to one O(2), one O(6), one O(8), one O(9), two equivalent O(3), and two equivalent O(5) atoms. In the third U site, U(3) is bonded in a body-centered cubic geometry to one O(1), one O(6), one O(7), one O(9), two equivalent O(2), and two equivalent O(4) atoms. In the fourth U site, U(4) is bonded in a body-centered cubic geometry to one O(1), one O(4), one O(5), one O(6), one O(7), one O(9), and two equivalent O(8) atoms. Th(1) is bonded in a body-centered cubic geometry to two equivalent O(3), two equivalent O(6), two equivalent O(7), and two equivalent O(8) atoms. There are nine inequivalent O sites. In the first O site, O(1) is bonded to one U(3), one U(4), and two equivalent U(1) atoms to form OU4 tetrahedra that share  a cornercorner with one O(5)U4 tetrahedra, corners with two equivalent O(3)ThU3 tetrahedra, corners with two equivalent O(6)ThU3 tetrahedra, corners with two equivalent O(7)ThU3 tetrahedra, corners with two equivalent O(8)ThU3 tetrahedra, corners with two equivalent O(2)U4 tetrahedra, corners with two equivalent O(9)U4 tetrahedra, corners with three equivalent O(4)U4 tetrahedra,  an edgeedge with one O(7)ThU3 tetrahedra,  an edgeedge with one O(1)U4 tetrahedra,  an edgeedge with one O(2)U4 tetrahedra,  an edgeedge with one O(4)U4 tetrahedra,  an edgeedge with one O(5)U4 tetrahedra, and  an edgeedge with one O(9)U4 tetrahedra. In the second O site, O(2) is bonded to one U(1), one U(2), and two equivalent U(3) atoms to form OU4 tetrahedra that share  a cornercorner with one O(3)ThU3 tetrahedra,  a cornercorner with one O(6)ThU3 tetrahedra,  a cornercorner with one O(8)ThU3 tetrahedra, corners with two equivalent O(1)U4 tetrahedra, corners with two equivalent O(9)U4 tetrahedra, corners with three equivalent O(7)ThU3 tetrahedra, corners with three equivalent O(4)U4 tetrahedra, corners with three equivalent O(5)U4 tetrahedra,  an edgeedge with one O(3)ThU3 tetrahedra,  an edgeedge with one O(6)ThU3 tetrahedra,  an edgeedge with one O(1)U4 tetrahedra,  an edgeedge with one O(2)U4 tetrahedra,  an edgeedge with one O(4)U4 tetrahedra, and  an edgeedge with one O(9)U4 tetrahedra. In the third O site, O(3) is bonded to one U(1), two equivalent U(2), and one Th(1) atom to form OThU3 tetrahedra that share  a cornercorner with one O(3)ThU3 tetrahedra,  a cornercorner with one O(7)ThU3 tetrahedra,  a cornercorner with one O(2)U4 tetrahedra,  a cornercorner with one O(4)U4 tetrahedra, corners with two equivalent O(6)ThU3 tetrahedra, corners with two equivalent O(8)ThU3 tetrahedra, corners with two equivalent O(1)U4 tetrahedra, corners with three equivalent O(5)U4 tetrahedra, corners with three equivalent O(9)U4 tetrahedra,  an edgeedge with one O(3)ThU3 tetrahedra,  an edgeedge with one O(6)ThU3 tetrahedra,  an edgeedge with one O(7)ThU3 tetrahedra,  an edgeedge with one O(8)ThU3 tetrahedra,  an edgeedge with one O(2)U4 tetrahedra, and  an edgeedge with one O(5)U4 tetrahedra. In the fourth O site, O(4) is bonded to one U(1), one U(4), and two equivalent U(3) atoms to form OU4 tetrahedra that share  a cornercorner with one O(3)ThU3 tetrahedra,  a cornercorner with one O(6)ThU3 tetrahedra, corners with two equivalent O(7)ThU3 tetrahedra, corners with two equivalent O(8)ThU3 tetrahedra, corners with two equivalent O(5)U4 tetrahedra, corners with two equivalent O(9)U4 tetrahedra, corners with three equivalent O(1)U4 tetrahedra, corners with three equivalent O(2)U4 tetrahedra,  an edgeedge with one O(6)ThU3 tetrahedra,  an edgeedge with one O(7)ThU3 tetrahedra,  an edgeedge with one O(1)U4 tetrahedra,  an edgeedge with one O(2)U4 tetrahedra,  an edgeedge with one O(4)U4 tetrahedra, and  an edgeedge with one O(9)U4 tetrahedra. In the fifth O site, O(5) is bonded to one U(1), one U(4), and two equivalent U(2) atoms to form OU4 tetrahedra that share  a cornercorner with one O(6)ThU3 tetrahedra,  a cornercorner with one O(1)U4 tetrahedra, corners with two equivalent O(7)ThU3 tetrahedra, corners with two equivalent O(8)ThU3 tetrahedra, corners with two equivalent O(4)U4 tetrahedra, corners with two equivalent O(9)U4 tetrahedra, corners with three equivalent O(3)ThU3 tetrahedra, corners with three equivalent O(2)U4 tetrahedra,  an edgeedge with one O(3)ThU3 tetrahedra,  an edgeedge with one O(6)ThU3 tetrahedra,  an edgeedge with one O(8)ThU3 tetrahedra,  an edgeedge with one O(1)U4 tetrahedra,  an edgeedge with one O(5)U4 tetrahedra, and  an edgeedge with one O(9)U4 tetrahedra. In the sixth O site, O(6) is bonded to one U(2), one U(3), one U(4), and one Th(1) atom to form OThU3 tetrahedra that share  a cornercorner with one O(6)ThU3 tetrahedra,  a cornercorner with one O(2)U4 tetrahedra,  a cornercorner with one O(4)U4 tetrahedra,  a cornercorner with one O(5)U4 tetrahedra, corners with two equivalent O(3)ThU3 tetrahedra, corners with two equivalent O(7)ThU3 tetrahedra, corners with two equivalent O(1)U4 tetrahedra, corners with three equivalent O(8)ThU3 tetrahedra, corners with three equivalent O(9)U4 tetrahedra,  an edgeedge with one O(3)ThU3 tetrahedra,  an edgeedge with one O(7)ThU3 tetrahedra,  an edgeedge with one O(8)ThU3 tetrahedra,  an edgeedge with one O(2)U4 tetrahedra,  an edgeedge with one O(4)U4 tetrahedra, and  an edgeedge with one O(5)U4 tetrahedra. In the seventh O site, O(7) is bonded to one U(1), one U(3), one U(4), and one Th(1) atom to form OThU3 tetrahedra that share  a cornercorner with one O(3)ThU3 tetrahedra,  a cornercorner with one O(7)ThU3 tetrahedra,  a cornercorner with one O(9)U4 tetrahedra, corners with two equivalent O(6)ThU3 tetrahedra, corners with two equivalent O(8)ThU3 tetrahedra, corners with two equivalent O(1)U4 tetrahedra, corners with two equivalent O(4)U4 tetrahedra, corners with two equivalent O(5)U4 tetrahedra, corners with three equivalent O(2)U4 tetrahedra,  an edgeedge with one O(3)ThU3 tetrahedra,  an edgeedge with one O(6)ThU3 tetrahedra,  an edgeedge with one O(8)ThU3 tetrahedra,  an edgeedge with one O(1)U4 tetrahedra,  an edgeedge with one O(4)U4 tetrahedra, and  an edgeedge with one O(9)U4 tetrahedra. In the eighth O site, O(8) is bonded to one U(2), two equivalent U(4), and one Th(1) atom to form OThU3 tetrahedra that share  a cornercorner with one O(8)ThU3 tetrahedra,  a cornercorner with one O(2)U4 tetrahedra,  a cornercorner with one O(9)U4 tetrahedra, corners with two equivalent O(3)ThU3 tetrahedra, corners with two equivalent O(7)ThU3 tetrahedra, corners with two equivalent O(1)U4 tetrahedra, corners with two equivalent O(4)U4 tetrahedra, corners with two equivalent O(5)U4 tetrahedra, corners with three equivalent O(6)ThU3 tetrahedra,  an edgeedge with one O(3)ThU3 tetrahedra,  an edgeedge with one O(6)ThU3 tetrahedra,  an edgeedge with one O(7)ThU3 tetrahedra,  an edgeedge with one O(8)ThU3 tetrahedra,  an edgeedge with one O(5)U4 tetrahedra, and  an edgeedge with one O(9)U4 tetrahedra. In the ninth O site, O(9) is bonded to one U(1), one U(2), one U(3), and one U(4) atom to form OU4 tetrahedra that share  a cornercorner with one O(7)ThU3 tetrahedra,  a cornercorner with one O(8)ThU3 tetrahedra, corners with two equivalent O(1)U4 tetrahedra, corners with two equivalent O(2)U4 tetrahedra, corners with two equivalent O(4)U4 tetrahedra, corners with two equivalent O(5)U4 tetrahedra, corners with three equivalent O(3)ThU3 tetrahedra, corners with three equivalent O(6)ThU3 tetrahedra,  an edgeedge with one O(7)ThU3 tetrahedra,  an edgeedge with one O(8)ThU3 tetrahedra,  an edgeedge with one O(1)U4 tetrahedra,  an edgeedge with one O(2)U4 tetrahedra,  an edgeedge with one O(4)U4 tetrahedra, and  an edgeedge with one O(5)U4 tetrahedra.
U8ThO18 is Fluorite-derived structured and crystallizes in the triclinic P-1 space group. There are four inequivalent U sites. In the first U site, U(1) is bonded in a body-centered cubic geometry to one O(2), one O(3), one O(4), one O(5), one O(7), one O(9), and two equivalent O(1) atoms. The U(1)-O(2) bond length is 2.42 Å. The U(1)-O(3) bond length is 2.33 Å. The U(1)-O(4) bond length is 2.35 Å. The U(1)-O(5) bond length is 2.31 Å. The U(1)-O(7) bond length is 2.41 Å. The U(1)-O(9) bond length is 2.40 Å. There is one shorter (2.32 Å) and one longer (2.40 Å) U(1)-O(1) bond length. In the second U site, U(2) is bonded in a body-centered cubic geometry to one O(2), one O(6), one O(8), one O(9), two equivalent O(3), and two equivalent O(5) atoms. The U(2)-O(2) bond length is 2.36 Å. The U(2)-O(6) bond length is 2.34 Å. The U(2)-O(8) bond length is 2.34 Å. The U(2)-O(9) bond length is 2.36 Å. There is one shorter (2.33 Å) and one longer (2.46 Å) U(2)-O(3) bond length. There is one shorter (2.31 Å) and one longer (2.44 Å) U(2)-O(5) bond length. In the third U site, U(3) is bonded in a body-centered cubic geometry to one O(1), one O(6), one O(7), one O(9), two equivalent O(2), and two equivalent O(4) atoms. The U(3)-O(1) bond length is 2.30 Å. The U(3)-O(6) bond length is 2.47 Å. The U(3)-O(7) bond length is 2.32 Å. The U(3)-O(9) bond length is 2.38 Å. There is one shorter (2.29 Å) and one longer (2.37 Å) U(3)-O(2) bond length. There is one shorter (2.34 Å) and one longer (2.45 Å) U(3)-O(4) bond length. In the fourth U site, U(4) is bonded in a body-centered cubic geometry to one O(1), one O(4), one O(5), one O(6), one O(7), one O(9), and two equivalent O(8) atoms. The U(4)-O(1) bond length is 2.43 Å. The U(4)-O(4) bond length is 2.33 Å. The U(4)-O(5) bond length is 2.42 Å. The U(4)-O(6) bond length is 2.34 Å. The U(4)-O(7) bond length is 2.37 Å. The U(4)-O(9) bond length is 2.31 Å. There is one shorter (2.31 Å) and one longer (2.45 Å) U(4)-O(8) bond length. Th(1) is bonded in a body-centered cubic geometry to two equivalent O(3), two equivalent O(6), two equivalent O(7), and two equivalent O(8) atoms. Both Th(1)-O(3) bond lengths are 2.42 Å. Both Th(1)-O(6) bond lengths are 2.38 Å. Both Th(1)-O(7) bond lengths are 2.41 Å. Both Th(1)-O(8) bond lengths are 2.42 Å. There are nine inequivalent O sites. In the first O site, O(1) is bonded to one U(3), one U(4), and two equivalent U(1) atoms to form OU4 tetrahedra that share  a cornercorner with one O(5)U4 tetrahedra, corners with two equivalent O(3)ThU3 tetrahedra, corners with two equivalent O(6)ThU3 tetrahedra, corners with two equivalent O(7)ThU3 tetrahedra, corners with two equivalent O(8)ThU3 tetrahedra, corners with two equivalent O(2)U4 tetrahedra, corners with two equivalent O(9)U4 tetrahedra, corners with three equivalent O(4)U4 tetrahedra,  an edgeedge with one O(7)ThU3 tetrahedra,  an edgeedge with one O(1)U4 tetrahedra,  an edgeedge with one O(2)U4 tetrahedra,  an edgeedge with one O(4)U4 tetrahedra,  an edgeedge with one O(5)U4 tetrahedra, and  an edgeedge with one O(9)U4 tetrahedra. In the second O site, O(2) is bonded to one U(1), one U(2), and two equivalent U(3) atoms to form OU4 tetrahedra that share  a cornercorner with one O(3)ThU3 tetrahedra,  a cornercorner with one O(6)ThU3 tetrahedra,  a cornercorner with one O(8)ThU3 tetrahedra, corners with two equivalent O(1)U4 tetrahedra, corners with two equivalent O(9)U4 tetrahedra, corners with three equivalent O(7)ThU3 tetrahedra, corners with three equivalent O(4)U4 tetrahedra, corners with three equivalent O(5)U4 tetrahedra,  an edgeedge with one O(3)ThU3 tetrahedra,  an edgeedge with one O(6)ThU3 tetrahedra,  an edgeedge with one O(1)U4 tetrahedra,  an edgeedge with one O(2)U4 tetrahedra,  an edgeedge with one O(4)U4 tetrahedra, and  an edgeedge with one O(9)U4 tetrahedra. In the third O site, O(3) is bonded to one U(1), two equivalent U(2), and one Th(1) atom to form OThU3 tetrahedra that share  a cornercorner with one O(3)ThU3 tetrahedra,  a cornercorner with one O(7)ThU3 tetrahedra,  a cornercorner with one O(2)U4 tetrahedra,  a cornercorner with one O(4)U4 tetrahedra, corners with two equivalent O(6)ThU3 tetrahedra, corners with two equivalent O(8)ThU3 tetrahedra, corners with two equivalent O(1)U4 tetrahedra, corners with three equivalent O(5)U4 tetrahedra, corners with three equivalent O(9)U4 tetrahedra,  an edgeedge with one O(3)ThU3 tetrahedra,  an edgeedge with one O(6)ThU3 tetrahedra,  an edgeedge with one O(7)ThU3 tetrahedra,  an edgeedge with one O(8)ThU3 tetrahedra,  an edgeedge with one O(2)U4 tetrahedra, and  an edgeedge with one O(5)U4 tetrahedra. In the fourth O site, O(4) is bonded to one U(1), one U(4), and two equivalent U(3) atoms to form OU4 tetrahedra that share  a cornercorner with one O(3)ThU3 tetrahedra,  a cornercorner with one O(6)ThU3 tetrahedra, corners with two equivalent O(7)ThU3 tetrahedra, corners with two equivalent O(8)ThU3 tetrahedra, corners with two equivalent O(5)U4 tetrahedra, corners with two equivalent O(9)U4 tetrahedra, corners with three equivalent O(1)U4 tetrahedra, corners with three equivalent O(2)U4 tetrahedra,  an edgeedge with one O(6)ThU3 tetrahedra,  an edgeedge with one O(7)ThU3 tetrahedra,  an edgeedge with one O(1)U4 tetrahedra,  an edgeedge with one O(2)U4 tetrahedra,  an edgeedge with one O(4)U4 tetrahedra, and  an edgeedge with one O(9)U4 tetrahedra. In the fifth O site, O(5) is bonded to one U(1), one U(4), and two equivalent U(2) atoms to form OU4 tetrahedra that share  a cornercorner with one O(6)ThU3 tetrahedra,  a cornercorner with one O(1)U4 tetrahedra, corners with two equivalent O(7)ThU3 tetrahedra, corners with two equivalent O(8)ThU3 tetrahedra, corners with two equivalent O(4)U4 tetrahedra, corners with two equivalent O(9)U4 tetrahedra, corners with three equivalent O(3)ThU3 tetrahedra, corners with three equivalent O(2)U4 tetrahedra,  an edgeedge with one O(3)ThU3 tetrahedra,  an edgeedge with one O(6)ThU3 tetrahedra,  an edgeedge with one O(8)ThU3 tetrahedra,  an edgeedge with one O(1)U4 tetrahedra,  an edgeedge with one O(5)U4 tetrahedra, and  an edgeedge with one O(9)U4 tetrahedra. In the sixth O site, O(6) is bonded to one U(2), one U(3), one U(4), and one Th(1) atom to form OThU3 tetrahedra that share  a cornercorner with one O(6)ThU3 tetrahedra,  a cornercorner with one O(2)U4 tetrahedra,  a cornercorner with one O(4)U4 tetrahedra,  a cornercorner with one O(5)U4 tetrahedra, corners with two equivalent O(3)ThU3 tetrahedra, corners with two equivalent O(7)ThU3 tetrahedra, corners with two equivalent O(1)U4 tetrahedra, corners with three equivalent O(8)ThU3 tetrahedra, corners with three equivalent O(9)U4 tetrahedra,  an edgeedge with one O(3)ThU3 tetrahedra,  an edgeedge with one O(7)ThU3 tetrahedra,  an edgeedge with one O(8)ThU3 tetrahedra,  an edgeedge with one O(2)U4 tetrahedra,  an edgeedge with one O(4)U4 tetrahedra, and  an edgeedge with one O(5)U4 tetrahedra. In the seventh O site, O(7) is bonded to one U(1), one U(3), one U(4), and one Th(1) atom to form OThU3 tetrahedra that share  a cornercorner with one O(3)ThU3 tetrahedra,  a cornercorner with one O(7)ThU3 tetrahedra,  a cornercorner with one O(9)U4 tetrahedra, corners with two equivalent O(6)ThU3 tetrahedra, corners with two equivalent O(8)ThU3 tetrahedra, corners with two equivalent O(1)U4 tetrahedra, corners with two equivalent O(4)U4 tetrahedra, corners with two equivalent O(5)U4 tetrahedra, corners with three equivalent O(2)U4 tetrahedra,  an edgeedge with one O(3)ThU3 tetrahedra,  an edgeedge with one O(6)ThU3 tetrahedra,  an edgeedge with one O(8)ThU3 tetrahedra,  an edgeedge with one O(1)U4 tetrahedra,  an edgeedge with one O(4)U4 tetrahedra, and  an edgeedge with one O(9)U4 tetrahedra. In the eighth O site, O(8) is bonded to one U(2), two equivalent U(4), and one Th(1) atom to form OThU3 tetrahedra that share  a cornercorner with one O(8)ThU3 tetrahedra,  a cornercorner with one O(2)U4 tetrahedra,  a cornercorner with one O(9)U4 tetrahedra, corners with two equivalent O(3)ThU3 tetrahedra, corners with two equivalent O(7)ThU3 tetrahedra, corners with two equivalent O(1)U4 tetrahedra, corners with two equivalent O(4)U4 tetrahedra, corners with two equivalent O(5)U4 tetrahedra, corners with three equivalent O(6)ThU3 tetrahedra,  an edgeedge with one O(3)ThU3 tetrahedra,  an edgeedge with one O(6)ThU3 tetrahedra,  an edgeedge with one O(7)ThU3 tetrahedra,  an edgeedge with one O(8)ThU3 tetrahedra,  an edgeedge with one O(5)U4 tetrahedra, and  an edgeedge with one O(9)U4 tetrahedra. In the ninth O site, O(9) is bonded to one U(1), one U(2), one U(3), and one U(4) atom to form OU4 tetrahedra that share  a cornercorner with one O(7)ThU3 tetrahedra,  a cornercorner with one O(8)ThU3 tetrahedra, corners with two equivalent O(1)U4 tetrahedra, corners with two equivalent O(2)U4 tetrahedra, corners with two equivalent O(4)U4 tetrahedra, corners with two equivalent O(5)U4 tetrahedra, corners with three equivalent O(3)ThU3 tetrahedra, corners with three equivalent O(6)ThU3 tetrahedra,  an edgeedge with one O(7)ThU3 tetrahedra,  an edgeedge with one O(8)ThU3 tetrahedra,  an edgeedge with one O(1)U4 tetrahedra,  an edgeedge with one O(2)U4 tetrahedra,  an edgeedge with one O(4)U4 tetrahedra, and  an edgeedge with one O(5)U4 tetrahedra.