Rb3GdV2O8 crystallizes in the trigonal P-3m1 space group. There are two inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 10-coordinate geometry to one O(1) and nine equivalent O(2) atoms. In the second Rb site, Rb(2) is bonded to six equivalent O(1) and six equivalent O(2) atoms to form distorted RbO12 cuboctahedra that share edges with six equivalent Rb(2)O12 cuboctahedra, edges with six equivalent V(1)O4 tetrahedra, and faces with two equivalent Gd(1)O6 octahedra. Gd(1) is bonded to six equivalent O(2) atoms to form GdO6 octahedra that share corners with six equivalent V(1)O4 tetrahedra and faces with two equivalent Rb(2)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 Gd(1)O6 octahedra and edges with three equivalent Rb(2)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 one Rb(1), three equivalent Rb(2), and one V(1) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Rb(2), three equivalent Rb(1), one Gd(1), and one V(1) atom.
Rb3GdV2O8 crystallizes in the trigonal P-3m1 space group. There are two inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 10-coordinate geometry to one O(1) and nine equivalent O(2) atoms. The Rb(1)-O(1) bond length is 2.76 Å. There are six shorter (3.07 Å) and three longer (3.31 Å) Rb(1)-O(2) bond lengths. In the second Rb site, Rb(2) is bonded to six equivalent O(1) and six equivalent O(2) atoms to form distorted RbO12 cuboctahedra that share edges with six equivalent Rb(2)O12 cuboctahedra, edges with six equivalent V(1)O4 tetrahedra, and faces with two equivalent Gd(1)O6 octahedra. All Rb(2)-O(1) bond lengths are 3.56 Å. All Rb(2)-O(2) bond lengths are 3.21 Å. Gd(1) is bonded to six equivalent O(2) atoms to form GdO6 octahedra that share corners with six equivalent V(1)O4 tetrahedra and faces with two equivalent Rb(2)O12 cuboctahedra. All Gd(1)-O(2) bond lengths are 2.32 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 Gd(1)O6 octahedra and edges with three equivalent Rb(2)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 one Rb(1), three equivalent Rb(2), and one V(1) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Rb(2), three equivalent Rb(1), one Gd(1), and one V(1) atom.