K8Tl11 crystallizes in the trigonal R-3c space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 7-coordinate geometry to one Tl(2), two equivalent Tl(3), and four equivalent Tl(1) atoms. In the second K site, K(2) is bonded in a distorted trigonal non-coplanar geometry to three equivalent Tl(2) and six equivalent Tl(1) atoms. There are three inequivalent Tl sites. In the first Tl site, Tl(1) is bonded in a 10-coordinate geometry to two equivalent K(2), four equivalent K(1), one Tl(1), one Tl(3), and two equivalent Tl(2) atoms. In the second Tl site, Tl(2) is bonded in a 10-coordinate geometry to two equivalent K(1), two equivalent K(2), two equivalent Tl(3), and four equivalent Tl(1) atoms. In the third Tl site, Tl(3) is bonded in a 12-coordinate geometry to six equivalent K(1), three equivalent Tl(1), and three equivalent Tl(2) atoms.
K8Tl11 crystallizes in the trigonal R-3c space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 7-coordinate geometry to one Tl(2), two equivalent Tl(3), and four equivalent Tl(1) atoms. The K(1)-Tl(2) bond length is 3.64 Å. There is one shorter (3.97 Å) and one longer (4.00 Å) K(1)-Tl(3) bond length. There are a spread of K(1)-Tl(1) bond distances ranging from 3.68-4.07 Å. In the second K site, K(2) is bonded in a distorted trigonal non-coplanar geometry to three equivalent Tl(2) and six equivalent Tl(1) atoms. All K(2)-Tl(2) bond lengths are 4.16 Å. There are three shorter (3.83 Å) and three longer (4.15 Å) K(2)-Tl(1) bond lengths. There are three inequivalent Tl sites. In the first Tl site, Tl(1) is bonded in a 10-coordinate geometry to two equivalent K(2), four equivalent K(1), one Tl(1), one Tl(3), and two equivalent Tl(2) atoms. The Tl(1)-Tl(1) bond length is 3.29 Å. The Tl(1)-Tl(3) bond length is 3.24 Å. There is one shorter (3.15 Å) and one longer (3.25 Å) Tl(1)-Tl(2) bond length. In the second Tl site, Tl(2) is bonded in a 10-coordinate geometry to two equivalent K(1), two equivalent K(2), two equivalent Tl(3), and four equivalent Tl(1) atoms. Both Tl(2)-Tl(3) bond lengths are 3.51 Å. In the third Tl site, Tl(3) is bonded in a 12-coordinate geometry to six equivalent K(1), three equivalent Tl(1), and three equivalent Tl(2) atoms.