K6NbTlAs4 crystallizes in the orthorhombic Pnma space group. There are four inequivalent K sites. In the first K site, K(1) is bonded in a 4-coordinate geometry to one K(3), one As(2), one As(3), and two equivalent As(1) atoms. In the second K site, K(2) is bonded in a 5-coordinate geometry to one As(2), two equivalent As(1), and two equivalent As(3) atoms. In the third K site, K(3) is bonded in a 13-coordinate geometry to one K(1), four equivalent K(4), one Nb(1), two equivalent Tl(1), one As(2), and four equivalent As(1) atoms. In the fourth K site, K(4) is bonded in a 5-coordinate geometry to two equivalent K(3), two equivalent Tl(1), one As(1), one As(2), and one As(3) atom. Nb(1) is bonded in a tetrahedral geometry to one K(3), one As(2), one As(3), and two equivalent As(1) atoms. Tl(1) is bonded in a 2-coordinate geometry to two equivalent K(3), four equivalent K(4), and two equivalent As(1) atoms. There are three inequivalent As sites. In the first As site, As(1) is bonded in a 7-coordinate geometry to one K(1), one K(4), two equivalent K(2), two equivalent K(3), one Nb(1), and one Tl(1) atom. In the second As site, As(2) is bonded in a 1-coordinate geometry to one K(1), one K(3), two equivalent K(2), two equivalent K(4), and one Nb(1) atom. In the third As site, As(3) is bonded in a 8-coordinate geometry to one K(1), two equivalent K(4), four equivalent K(2), and one Nb(1) atom.
K6NbTlAs4 crystallizes in the orthorhombic Pnma space group. There are four inequivalent K sites. In the first K site, K(1) is bonded in a 4-coordinate geometry to one K(3), one As(2), one As(3), and two equivalent As(1) atoms. The K(1)-K(3) bond length is 3.53 Å. The K(1)-As(2) bond length is 3.39 Å. The K(1)-As(3) bond length is 3.19 Å. Both K(1)-As(1) bond lengths are 3.47 Å. In the second K site, K(2) is bonded in a 5-coordinate geometry to one As(2), two equivalent As(1), and two equivalent As(3) atoms. The K(2)-As(2) bond length is 3.47 Å. There is one shorter (3.48 Å) and one longer (3.57 Å) K(2)-As(1) bond length. There is one shorter (3.28 Å) and one longer (3.61 Å) K(2)-As(3) bond length. In the third K site, K(3) is bonded in a 13-coordinate geometry to one K(1), four equivalent K(4), one Nb(1), two equivalent Tl(1), one As(2), and four equivalent As(1) atoms. There are two shorter (3.69 Å) and two longer (3.88 Å) K(3)-K(4) bond lengths. The K(3)-Nb(1) bond length is 3.51 Å. There is one shorter (4.04 Å) and one longer (4.10 Å) K(3)-Tl(1) bond length. The K(3)-As(2) bond length is 3.50 Å. There are two shorter (3.56 Å) and two longer (3.94 Å) K(3)-As(1) bond lengths. In the fourth K site, K(4) is bonded in a 5-coordinate geometry to two equivalent K(3), two equivalent Tl(1), one As(1), one As(2), and one As(3) atom. There is one shorter (3.63 Å) and one longer (3.69 Å) K(4)-Tl(1) bond length. The K(4)-As(1) bond length is 3.50 Å. The K(4)-As(2) bond length is 3.37 Å. The K(4)-As(3) bond length is 3.43 Å. Nb(1) is bonded in a tetrahedral geometry to one K(3), one As(2), one As(3), and two equivalent As(1) atoms. The Nb(1)-As(2) bond length is 2.49 Å. The Nb(1)-As(3) bond length is 2.51 Å. Both Nb(1)-As(1) bond lengths are 2.56 Å. Tl(1) is bonded in a 2-coordinate geometry to two equivalent K(3), four equivalent K(4), and two equivalent As(1) atoms. Both Tl(1)-As(1) bond lengths are 2.89 Å. There are three inequivalent As sites. In the first As site, As(1) is bonded in a 7-coordinate geometry to one K(1), one K(4), two equivalent K(2), two equivalent K(3), one Nb(1), and one Tl(1) atom. In the second As site, As(2) is bonded in a 1-coordinate geometry to one K(1), one K(3), two equivalent K(2), two equivalent K(4), and one Nb(1) atom. In the third As site, As(3) is bonded in a 8-coordinate geometry to one K(1), two equivalent K(4), four equivalent K(2), and one Nb(1) atom.