RbK2MgGdV2O8 crystallizes in the monoclinic Cm space group. Rb(1) is bonded in a 8-coordinate geometry to one Mg(1), one O(2), one O(3), one O(6), two equivalent O(4), and two equivalent O(5) atoms. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 7-coordinate geometry to one O(6), two equivalent O(3), and four equivalent O(4) atoms. In the second K site, K(2) is bonded in a 7-coordinate geometry to one O(5), two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms. Mg(1) is bonded in a distorted trigonal planar geometry to one Rb(1), one O(5), and two equivalent O(1) atoms. Gd(1) is bonded to one O(2), one O(3), two equivalent O(1), and two equivalent O(4) atoms to form GdO6 octahedra that share corners with three equivalent V(1)O4 tetrahedra and corners with three equivalent V(2)O4 tetrahedra. There are two inequivalent V sites. In the first V site, V(1) is bonded to one O(2), one O(6), and two equivalent O(1) atoms to form VO4 tetrahedra that share corners with three equivalent Gd(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 16-25°. In the second V site, V(2) is bonded to one O(3), one O(5), and two equivalent O(4) atoms to form VO4 tetrahedra that share corners with three equivalent Gd(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 9-16°. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one K(2), one Mg(1), one Gd(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(2), one Gd(1), and one V(1) atom. In the third O site, O(3) is bonded in a 5-coordinate geometry to one Rb(1), two equivalent K(1), one Gd(1), and one V(2) atom. In the fourth O site, O(4) is bonded in a 6-coordinate geometry to one Rb(1), one K(2), two equivalent K(1), one Gd(1), and one V(2) atom. In the fifth O site, O(5) is bonded in a distorted bent 120 degrees geometry to two equivalent Rb(1), one K(2), one Mg(1), and one V(2) atom. In the sixth O site, O(6) is bonded in a distorted T-shaped geometry to one Rb(1), one K(1), and one V(1) atom.
RbK2MgGdV2O8 crystallizes in the monoclinic Cm space group. Rb(1) is bonded in a 8-coordinate geometry to one Mg(1), one O(2), one O(3), one O(6), two equivalent O(4), and two equivalent O(5) atoms. The Rb(1)-Mg(1) bond length is 3.13 Å. The Rb(1)-O(2) bond length is 2.98 Å. The Rb(1)-O(3) bond length is 3.02 Å. The Rb(1)-O(6) bond length is 2.76 Å. Both Rb(1)-O(4) bond lengths are 2.87 Å. Both Rb(1)-O(5) bond lengths are 3.34 Å. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 7-coordinate geometry to one O(6), two equivalent O(3), and four equivalent O(4) atoms. The K(1)-O(6) bond length is 2.64 Å. Both K(1)-O(3) bond lengths are 3.05 Å. There are two shorter (3.11 Å) and two longer (3.16 Å) K(1)-O(4) bond lengths. In the second K site, K(2) is bonded in a 7-coordinate geometry to one O(5), two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms. The K(2)-O(5) bond length is 3.00 Å. Both K(2)-O(1) bond lengths are 2.82 Å. Both K(2)-O(2) bond lengths are 3.12 Å. Both K(2)-O(4) bond lengths are 2.89 Å. Mg(1) is bonded in a distorted trigonal planar geometry to one Rb(1), one O(5), and two equivalent O(1) atoms. The Mg(1)-O(5) bond length is 1.91 Å. Both Mg(1)-O(1) bond lengths are 1.95 Å. Gd(1) is bonded to one O(2), one O(3), two equivalent O(1), and two equivalent O(4) atoms to form GdO6 octahedra that share corners with three equivalent V(1)O4 tetrahedra and corners with three equivalent V(2)O4 tetrahedra. The Gd(1)-O(2) bond length is 2.38 Å. The Gd(1)-O(3) bond length is 2.38 Å. Both Gd(1)-O(1) bond lengths are 2.39 Å. Both Gd(1)-O(4) bond lengths are 2.23 Å. There are two inequivalent V sites. In the first V site, V(1) is bonded to one O(2), one O(6), and two equivalent O(1) atoms to form VO4 tetrahedra that share corners with three equivalent Gd(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 16-25°. The V(1)-O(2) bond length is 1.81 Å. The V(1)-O(6) bond length is 1.73 Å. Both V(1)-O(1) bond lengths are 1.91 Å. In the second V site, V(2) is bonded to one O(3), one O(5), and two equivalent O(4) atoms to form VO4 tetrahedra that share corners with three equivalent Gd(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 9-16°. The V(2)-O(3) bond length is 1.80 Å. The V(2)-O(5) bond length is 1.83 Å. Both V(2)-O(4) bond lengths are 1.85 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one K(2), one Mg(1), one Gd(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(2), one Gd(1), and one V(1) atom. In the third O site, O(3) is bonded in a 5-coordinate geometry to one Rb(1), two equivalent K(1), one Gd(1), and one V(2) atom. In the fourth O site, O(4) is bonded in a 6-coordinate geometry to one Rb(1), one K(2), two equivalent K(1), one Gd(1), and one V(2) atom. In the fifth O site, O(5) is bonded in a distorted bent 120 degrees geometry to two equivalent Rb(1), one K(2), one Mg(1), and one V(2) atom. In the sixth O site, O(6) is bonded in a distorted T-shaped geometry to one Rb(1), one K(1), and one V(1) atom.