Cs3Sc2Cl9 crystallizes in the trigonal R-3c space group. Cs(1) is bonded to four equivalent Cl(1) and eight equivalent Cl(2) atoms to form CsCl12 cuboctahedra that share corners with six equivalent Cs(1)Cl12 cuboctahedra, corners with four equivalent Sc(1)Cl6 octahedra, faces with eight equivalent Cs(1)Cl12 cuboctahedra, and faces with four equivalent Sc(1)Cl6 octahedra. The corner-sharing octahedral tilt angles range from 10-28°. Sc(1) is bonded to three equivalent Cl(1) and three equivalent Cl(2) atoms to form ScCl6 octahedra that share corners with six equivalent Cs(1)Cl12 cuboctahedra, faces with six equivalent Cs(1)Cl12 cuboctahedra, and  a faceface with one Sc(1)Cl6 octahedra. There are two inequivalent Cl sites. In the first Cl site, Cl(2) is bonded in a distorted single-bond geometry to four equivalent Cs(1) and one Sc(1) atom. In the second Cl site, Cl(1) is bonded in a distorted L-shaped geometry to four equivalent Cs(1) and two equivalent Sc(1) atoms.
Cs3Sc2Cl9 crystallizes in the trigonal R-3c space group. Cs(1) is bonded to four equivalent Cl(1) and eight equivalent Cl(2) atoms to form CsCl12 cuboctahedra that share corners with six equivalent Cs(1)Cl12 cuboctahedra, corners with four equivalent Sc(1)Cl6 octahedra, faces with eight equivalent Cs(1)Cl12 cuboctahedra, and faces with four equivalent Sc(1)Cl6 octahedra. The corner-sharing octahedral tilt angles range from 10-28°. There are two shorter (3.75 Å) and two longer (3.81 Å) Cs(1)-Cl(1) bond lengths. There are a spread of Cs(1)-Cl(2) bond distances ranging from 3.65-3.81 Å. Sc(1) is bonded to three equivalent Cl(1) and three equivalent Cl(2) atoms to form ScCl6 octahedra that share corners with six equivalent Cs(1)Cl12 cuboctahedra, faces with six equivalent Cs(1)Cl12 cuboctahedra, and  a faceface with one Sc(1)Cl6 octahedra. All Sc(1)-Cl(1) bond lengths are 2.61 Å. All Sc(1)-Cl(2) bond lengths are 2.41 Å. There are two inequivalent Cl sites. In the first Cl site, Cl(2) is bonded in a distorted single-bond geometry to four equivalent Cs(1) and one Sc(1) atom. In the second Cl site, Cl(1) is bonded in a distorted L-shaped geometry to four equivalent Cs(1) and two equivalent Sc(1) atoms.