Rb2NbCl6 crystallizes in the monoclinic C2/m space group. Rb(1) is bonded to four equivalent Cl(1), four equivalent Cl(2), and four equivalent Cl(3) atoms to form RbCl12 cuboctahedra that share corners with twelve equivalent Rb(1)Cl12 cuboctahedra, faces with six equivalent Rb(1)Cl12 cuboctahedra, and faces with four equivalent Nb(1)Cl6 octahedra. Nb(1) is bonded to two equivalent Cl(1), two equivalent Cl(2), and two equivalent Cl(3) atoms to form NbCl6 octahedra that share faces with eight equivalent Rb(1)Cl12 cuboctahedra. There are three inequivalent Cl sites. In the first Cl site, Cl(1) is bonded in a distorted single-bond geometry to four equivalent Rb(1) and one Nb(1) atom. In the second Cl site, Cl(2) is bonded in a distorted single-bond geometry to four equivalent Rb(1) and one Nb(1) atom. In the third Cl site, Cl(3) is bonded in a distorted single-bond geometry to four equivalent Rb(1) and one Nb(1) atom.
Rb2NbCl6 crystallizes in the monoclinic C2/m space group. Rb(1) is bonded to four equivalent Cl(1), four equivalent Cl(2), and four equivalent Cl(3) atoms to form RbCl12 cuboctahedra that share corners with twelve equivalent Rb(1)Cl12 cuboctahedra, faces with six equivalent Rb(1)Cl12 cuboctahedra, and faces with four equivalent Nb(1)Cl6 octahedra. There are two shorter (3.63 Å) and two longer (3.64 Å) Rb(1)-Cl(1) bond lengths. There are two shorter (3.54 Å) and two longer (3.58 Å) Rb(1)-Cl(2) bond lengths. There are two shorter (3.57 Å) and two longer (3.58 Å) Rb(1)-Cl(3) bond lengths. Nb(1) is bonded to two equivalent Cl(1), two equivalent Cl(2), and two equivalent Cl(3) atoms to form NbCl6 octahedra that share faces with eight equivalent Rb(1)Cl12 cuboctahedra. Both Nb(1)-Cl(1) bond lengths are 2.41 Å. Both Nb(1)-Cl(2) bond lengths are 2.46 Å. Both Nb(1)-Cl(3) bond lengths are 2.44 Å. There are three inequivalent Cl sites. In the first Cl site, Cl(1) is bonded in a distorted single-bond geometry to four equivalent Rb(1) and one Nb(1) atom. In the second Cl site, Cl(2) is bonded in a distorted single-bond geometry to four equivalent Rb(1) and one Nb(1) atom. In the third Cl site, Cl(3) is bonded in a distorted single-bond geometry to four equivalent Rb(1) and one Nb(1) atom.