RbK2LuV2O8 crystallizes in the trigonal P-3m1 space group. Rb(1) is bonded to six equivalent O(1) and six equivalent O(2) atoms to form RbO12 cuboctahedra that share edges with six equivalent Rb(1)O12 cuboctahedra, edges with six equivalent V(1)O4 tetrahedra, and faces with two equivalent Lu(1)O6 octahedra. K(1) is bonded in a 7-coordinate geometry to one O(1) and six equivalent O(2) atoms. Lu(1) is bonded to six equivalent O(2) atoms to form LuO6 octahedra that share corners with six equivalent V(1)O4 tetrahedra and faces with two equivalent Rb(1)O12 cuboctahedra. V(1) is bonded to one O(1) and three equivalent O(2) atoms to form VO4 tetrahedra that share corners with three equivalent Lu(1)O6 octahedra and edges with three equivalent Rb(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 16°. There are two inequivalent O sites. In the first O site, O(1) is bonded in a distorted linear geometry to three equivalent Rb(1), one K(1), and one V(1) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Rb(1), two equivalent K(1), one Lu(1), and one V(1) atom.
RbK2LuV2O8 crystallizes in the trigonal P-3m1 space group. Rb(1) is bonded to six equivalent O(1) and six equivalent O(2) atoms to form RbO12 cuboctahedra that share edges with six equivalent Rb(1)O12 cuboctahedra, edges with six equivalent V(1)O4 tetrahedra, and faces with two equivalent Lu(1)O6 octahedra. All Rb(1)-O(1) bond lengths are 3.46 Å. All Rb(1)-O(2) bond lengths are 3.13 Å. K(1) is bonded in a 7-coordinate geometry to one O(1) and six equivalent O(2) atoms. The K(1)-O(1) bond length is 2.61 Å. All K(1)-O(2) bond lengths are 2.99 Å. Lu(1) is bonded to six equivalent O(2) atoms to form LuO6 octahedra that share corners with six equivalent V(1)O4 tetrahedra and faces with two equivalent Rb(1)O12 cuboctahedra. All Lu(1)-O(2) bond lengths are 2.21 Å. V(1) is bonded to one O(1) and three equivalent O(2) atoms to form VO4 tetrahedra that share corners with three equivalent Lu(1)O6 octahedra and edges with three equivalent Rb(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 16°. The V(1)-O(1) bond length is 1.68 Å. All V(1)-O(2) bond lengths are 1.77 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded in a distorted linear geometry to three equivalent Rb(1), one K(1), and one V(1) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Rb(1), two equivalent K(1), one Lu(1), and one V(1) atom.