Rb3Mo2Cl9 crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Rb sites. In the first Rb site, Rb(1) is bonded to six equivalent Cl(1) and six equivalent Cl(2) atoms to form RbCl12 cuboctahedra that share corners with six equivalent Rb(1)Cl12 cuboctahedra, corners with six equivalent Rb(2)Cl12 cuboctahedra, faces with six equivalent Rb(2)Cl12 cuboctahedra, and faces with six equivalent Mo(1)Cl6 octahedra. In the second Rb site, Rb(2) is bonded to three equivalent Cl(2) and nine equivalent Cl(1) atoms to form RbCl12 cuboctahedra that share corners with three equivalent Rb(1)Cl12 cuboctahedra, corners with six equivalent Rb(2)Cl12 cuboctahedra, corners with three equivalent Mo(1)Cl6 octahedra, faces with three equivalent Rb(1)Cl12 cuboctahedra, faces with four equivalent Rb(2)Cl12 cuboctahedra, and faces with four equivalent Mo(1)Cl6 octahedra. The corner-sharing octahedral tilt angles are 23°. Mo(1) is bonded to three equivalent Cl(1) and three equivalent Cl(2) atoms to form MoCl6 octahedra that share corners with three equivalent Rb(2)Cl12 cuboctahedra, faces with three equivalent Rb(1)Cl12 cuboctahedra, faces with four equivalent Rb(2)Cl12 cuboctahedra, and  a faceface with one Mo(1)Cl6 octahedra. There are two inequivalent Cl sites. In the first Cl site, Cl(1) is bonded to one Rb(1), three equivalent Rb(2), and one Mo(1) atom to form a mixture of distorted corner, edge, and face-sharing ClRb4Mo square pyramids. In the second Cl site, Cl(2) is bonded in a 2-coordinate geometry to two equivalent Rb(1), two equivalent Rb(2), and two equivalent Mo(1) atoms.
Rb3Mo2Cl9 crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Rb sites. In the first Rb site, Rb(1) is bonded to six equivalent Cl(1) and six equivalent Cl(2) atoms to form RbCl12 cuboctahedra that share corners with six equivalent Rb(1)Cl12 cuboctahedra, corners with six equivalent Rb(2)Cl12 cuboctahedra, faces with six equivalent Rb(2)Cl12 cuboctahedra, and faces with six equivalent Mo(1)Cl6 octahedra. All Rb(1)-Cl(1) bond lengths are 3.50 Å. All Rb(1)-Cl(2) bond lengths are 3.58 Å. In the second Rb site, Rb(2) is bonded to three equivalent Cl(2) and nine equivalent Cl(1) atoms to form RbCl12 cuboctahedra that share corners with three equivalent Rb(1)Cl12 cuboctahedra, corners with six equivalent Rb(2)Cl12 cuboctahedra, corners with three equivalent Mo(1)Cl6 octahedra, faces with three equivalent Rb(1)Cl12 cuboctahedra, faces with four equivalent Rb(2)Cl12 cuboctahedra, and faces with four equivalent Mo(1)Cl6 octahedra. The corner-sharing octahedral tilt angles are 23°. All Rb(2)-Cl(2) bond lengths are 3.80 Å. There are three shorter (3.45 Å) and six longer (3.61 Å) Rb(2)-Cl(1) bond lengths. Mo(1) is bonded to three equivalent Cl(1) and three equivalent Cl(2) atoms to form MoCl6 octahedra that share corners with three equivalent Rb(2)Cl12 cuboctahedra, faces with three equivalent Rb(1)Cl12 cuboctahedra, faces with four equivalent Rb(2)Cl12 cuboctahedra, and  a faceface with one Mo(1)Cl6 octahedra. All Mo(1)-Cl(1) bond lengths are 2.40 Å. All Mo(1)-Cl(2) bond lengths are 2.48 Å. There are two inequivalent Cl sites. In the first Cl site, Cl(1) is bonded to one Rb(1), three equivalent Rb(2), and one Mo(1) atom to form a mixture of distorted corner, edge, and face-sharing ClRb4Mo square pyramids. In the second Cl site, Cl(2) is bonded in a 2-coordinate geometry to two equivalent Rb(1), two equivalent Rb(2), and two equivalent Mo(1) atoms.