Cs3Mo2Cl9 crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Cs sites. In the first Cs site, Cs(1) is bonded to six equivalent Cl(1) and six equivalent Cl(2) atoms to form CsCl12 cuboctahedra that share corners with six equivalent Cs(1)Cl12 cuboctahedra, corners with six equivalent Cs(2)Cl12 cuboctahedra, faces with six equivalent Cs(2)Cl12 cuboctahedra, and faces with six equivalent Mo(1)Cl6 octahedra. In the second Cs site, Cs(2) is bonded to three equivalent Cl(1) and nine equivalent Cl(2) atoms to form CsCl12 cuboctahedra that share corners with three equivalent Cs(1)Cl12 cuboctahedra, corners with six equivalent Cs(2)Cl12 cuboctahedra, corners with three equivalent Mo(1)Cl6 octahedra, faces with three equivalent Cs(1)Cl12 cuboctahedra, faces with four equivalent Cs(2)Cl12 cuboctahedra, and faces with four equivalent Mo(1)Cl6 octahedra. The corner-sharing octahedral tilt angles are 22°. 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 Cs(2)Cl12 cuboctahedra, faces with three equivalent Cs(1)Cl12 cuboctahedra, faces with four equivalent Cs(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 in a 2-coordinate geometry to two equivalent Cs(1), two equivalent Cs(2), and two equivalent Mo(1) atoms. In the second Cl site, Cl(2) is bonded to one Cs(1), three equivalent Cs(2), and one Mo(1) atom to form a mixture of distorted face, corner, and edge-sharing ClCs4Mo square pyramids.
Cs3Mo2Cl9 crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Cs sites. In the first Cs site, Cs(1) is bonded to six equivalent Cl(1) and six equivalent Cl(2) atoms to form CsCl12 cuboctahedra that share corners with six equivalent Cs(1)Cl12 cuboctahedra, corners with six equivalent Cs(2)Cl12 cuboctahedra, faces with six equivalent Cs(2)Cl12 cuboctahedra, and faces with six equivalent Mo(1)Cl6 octahedra. All Cs(1)-Cl(1) bond lengths are 3.69 Å. All Cs(1)-Cl(2) bond lengths are 3.58 Å. In the second Cs site, Cs(2) is bonded to three equivalent Cl(1) and nine equivalent Cl(2) atoms to form CsCl12 cuboctahedra that share corners with three equivalent Cs(1)Cl12 cuboctahedra, corners with six equivalent Cs(2)Cl12 cuboctahedra, corners with three equivalent Mo(1)Cl6 octahedra, faces with three equivalent Cs(1)Cl12 cuboctahedra, faces with four equivalent Cs(2)Cl12 cuboctahedra, and faces with four equivalent Mo(1)Cl6 octahedra. The corner-sharing octahedral tilt angles are 22°. All Cs(2)-Cl(1) bond lengths are 3.88 Å. There are three shorter (3.61 Å) and six longer (3.72 Å) Cs(2)-Cl(2) 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 Cs(2)Cl12 cuboctahedra, faces with three equivalent Cs(1)Cl12 cuboctahedra, faces with four equivalent Cs(2)Cl12 cuboctahedra, and  a faceface with one Mo(1)Cl6 octahedra. All Mo(1)-Cl(1) bond lengths are 2.49 Å. All Mo(1)-Cl(2) bond lengths are 2.41 Å. There are two inequivalent Cl sites. In the first Cl site, Cl(1) is bonded in a 2-coordinate geometry to two equivalent Cs(1), two equivalent Cs(2), and two equivalent Mo(1) atoms. In the second Cl site, Cl(2) is bonded to one Cs(1), three equivalent Cs(2), and one Mo(1) atom to form a mixture of distorted face, corner, and edge-sharing ClCs4Mo square pyramids.