RbCr(SO4)2 crystallizes in the monoclinic C2 space group. Rb(1) is bonded to two equivalent O(2), two equivalent O(3), two equivalent O(4), and six equivalent O(1) atoms to form RbO12 cuboctahedra that share edges with six equivalent Rb(1)O12 cuboctahedra, edges with six equivalent S(1)O4 tetrahedra, and faces with two equivalent Cr(1)O6 octahedra. Cr(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form CrO6 octahedra that share corners with six equivalent S(1)O4 tetrahedra and faces with two equivalent Rb(1)O12 cuboctahedra. S(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SO4 tetrahedra that share corners with three equivalent Cr(1)O6 octahedra and edges with three equivalent Rb(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 25-26°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a single-bond geometry to three equivalent Rb(1) and one S(1) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Rb(1), one Cr(1), and one S(1) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Rb(1), one Cr(1), and one S(1) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Rb(1), one Cr(1), and one S(1) atom.
RbCr(SO4)2 crystallizes in the monoclinic C2 space group. Rb(1) is bonded to two equivalent O(2), two equivalent O(3), two equivalent O(4), and six equivalent O(1) atoms to form RbO12 cuboctahedra that share edges with six equivalent Rb(1)O12 cuboctahedra, edges with six equivalent S(1)O4 tetrahedra, and faces with two equivalent Cr(1)O6 octahedra. Both Rb(1)-O(2) bond lengths are 3.36 Å. Both Rb(1)-O(3) bond lengths are 3.36 Å. Both Rb(1)-O(4) bond lengths are 3.36 Å. There are four shorter (3.10 Å) and two longer (3.12 Å) Rb(1)-O(1) bond lengths. Cr(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form CrO6 octahedra that share corners with six equivalent S(1)O4 tetrahedra and faces with two equivalent Rb(1)O12 cuboctahedra. Both Cr(1)-O(2) bond lengths are 2.01 Å. Both Cr(1)-O(3) bond lengths are 2.00 Å. Both Cr(1)-O(4) bond lengths are 2.01 Å. S(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SO4 tetrahedra that share corners with three equivalent Cr(1)O6 octahedra and edges with three equivalent Rb(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 25-26°. The S(1)-O(1) bond length is 1.46 Å. The S(1)-O(2) bond length is 1.49 Å. The S(1)-O(3) bond length is 1.49 Å. The S(1)-O(4) bond length is 1.49 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a single-bond geometry to three equivalent Rb(1) and one S(1) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Rb(1), one Cr(1), and one S(1) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Rb(1), one Cr(1), and one S(1) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Rb(1), one Cr(1), and one S(1) atom.