Tl2VNb6Cl18 crystallizes in the trigonal R-3 space group. The structure consists of six 7440-28-0 atoms inside a Nb6VCl18 framework. In the Nb6VCl18 framework, Nb(1) is bonded to one Cl(3), two equivalent Cl(1), and two equivalent Cl(2) atoms to form distorted NbCl5 square pyramids that share  a cornercorner with one V(1)Cl6 octahedra and corners with four equivalent Nb(1)Cl5 square pyramids. The corner-sharing octahedral tilt angles are 44°. V(1) is bonded to six equivalent Cl(3) atoms to form VCl6 octahedra that share corners with six equivalent Nb(1)Cl5 square pyramids. There are three inequivalent Cl sites. In the first Cl site, Cl(1) is bonded in a 2-coordinate geometry to two equivalent Nb(1) atoms. In the second Cl site, Cl(2) is bonded in a 2-coordinate geometry to two equivalent Nb(1) atoms. In the third Cl site, Cl(3) is bonded in a distorted bent 150 degrees geometry to one Nb(1) and one V(1) atom.
Tl2VNb6Cl18 crystallizes in the trigonal R-3 space group. The structure consists of six 7440-28-0 atoms inside a Nb6VCl18 framework. In the Nb6VCl18 framework, Nb(1) is bonded to one Cl(3), two equivalent Cl(1), and two equivalent Cl(2) atoms to form distorted NbCl5 square pyramids that share  a cornercorner with one V(1)Cl6 octahedra and corners with four equivalent Nb(1)Cl5 square pyramids. The corner-sharing octahedral tilt angles are 44°. The Nb(1)-Cl(3) bond length is 2.69 Å. Both Nb(1)-Cl(1) bond lengths are 2.47 Å. There is one shorter (2.47 Å) and one longer (2.48 Å) Nb(1)-Cl(2) bond length. V(1) is bonded to six equivalent Cl(3) atoms to form VCl6 octahedra that share corners with six equivalent Nb(1)Cl5 square pyramids. All V(1)-Cl(3) bond lengths are 2.55 Å. There are three inequivalent Cl sites. In the first Cl site, Cl(1) is bonded in a 2-coordinate geometry to two equivalent Nb(1) atoms. In the second Cl site, Cl(2) is bonded in a 2-coordinate geometry to two equivalent Nb(1) atoms. In the third Cl site, Cl(3) is bonded in a distorted bent 150 degrees geometry to one Nb(1) and one V(1) atom.