RbCr(SO4)2 crystallizes in the trigonal P-3c1 space group. Rb(1) is bonded to six equivalent O(1) atoms to form distorted RbO6 cuboctahedra that share corners with six equivalent S(1)O4 tetrahedra and edges with six equivalent Rb(1)O6 cuboctahedra. Cr(1) is bonded to six equivalent O(2) atoms to form CrO6 octahedra that share corners with six equivalent S(1)O4 tetrahedra. S(1) is bonded to one O(1) and three equivalent O(2) atoms to form SO4 tetrahedra that share corners with three equivalent Rb(1)O6 cuboctahedra and corners with three equivalent Cr(1)O6 octahedra. The corner-sharing octahedral tilt angles are 40°. There are two inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to three equivalent Rb(1) and one S(1) atom. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to one Cr(1) and one S(1) atom.
RbCr(SO4)2 crystallizes in the trigonal P-3c1 space group. Rb(1) is bonded to six equivalent O(1) atoms to form distorted RbO6 cuboctahedra that share corners with six equivalent S(1)O4 tetrahedra and edges with six equivalent Rb(1)O6 cuboctahedra. All Rb(1)-O(1) bond lengths are 3.05 Å. Cr(1) is bonded to six equivalent O(2) atoms to form CrO6 octahedra that share corners with six equivalent S(1)O4 tetrahedra. All Cr(1)-O(2) bond lengths are 2.01 Å. S(1) is bonded to one O(1) and three equivalent O(2) atoms to form SO4 tetrahedra that share corners with three equivalent Rb(1)O6 cuboctahedra and corners with three equivalent Cr(1)O6 octahedra. The corner-sharing octahedral tilt angles are 40°. The S(1)-O(1) bond length is 1.46 Å. All S(1)-O(2) bond lengths are 1.50 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to three equivalent Rb(1) and one S(1) atom. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to one Cr(1) and one S(1) atom.