RbK2MgTbV2O8 is Pb (Zr_0.50 Ti_0.48) O_3-derived structured and crystallizes in the monoclinic Cm space group. Rb(1) is bonded in a 7-coordinate geometry to one O(2), one O(3), one O(5), two equivalent O(1), and two equivalent O(6) 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(1), two equivalent O(3), and two equivalent O(4) atoms. In the second K site, K(2) is bonded in a 7-coordinate geometry to one Mg(1), one O(5), one O(6), two equivalent O(1), and two equivalent O(2) atoms. Mg(1) is bonded in a 5-coordinate geometry to one K(2), one O(3), two equivalent O(1), and two equivalent O(4) atoms. Tb(1) is bonded to one O(2), one O(3), two equivalent O(1), and two equivalent O(4) atoms to form TbO6 octahedra that share corners with three equivalent V(1)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 Tb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 20-51°. In the second V site, V(2) is bonded in a rectangular see-saw-like geometry to one O(3), one O(5), and two equivalent O(4) atoms. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to one Rb(1), one K(1), one K(2), one Mg(1), one Tb(1), and one V(1) atom. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Rb(1), two equivalent K(2), one Tb(1), and one V(1) atom. In the third O site, O(3) is bonded to one Rb(1), two equivalent K(1), one Mg(1), one Tb(1), and one V(2) atom to form distorted corner-sharing OK2RbTbMgV octahedra. The corner-sharing octahedral tilt angles are 4°. In the fourth O site, O(4) is bonded in a distorted rectangular see-saw-like geometry to one K(1), one Mg(1), one Tb(1), and one V(2) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Rb(1), one K(2), and one V(2) atom. In the sixth O site, O(6) is bonded in a distorted single-bond geometry to two equivalent Rb(1), one K(1), one K(2), and one V(1) atom.
RbK2MgTbV2O8 is Pb (Zr_0.50 Ti_0.48) O_3-derived structured and crystallizes in the monoclinic Cm space group. Rb(1) is bonded in a 7-coordinate geometry to one O(2), one O(3), one O(5), two equivalent O(1), and two equivalent O(6) atoms. The Rb(1)-O(2) bond length is 3.00 Å. The Rb(1)-O(3) bond length is 3.00 Å. The Rb(1)-O(5) bond length is 2.94 Å. Both Rb(1)-O(1) bond lengths are 3.23 Å. Both Rb(1)-O(6) bond lengths are 3.03 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(1), two equivalent O(3), and two equivalent O(4) atoms. The K(1)-O(6) bond length is 3.07 Å. Both K(1)-O(1) bond lengths are 3.08 Å. Both K(1)-O(3) bond lengths are 2.92 Å. Both K(1)-O(4) bond lengths are 2.89 Å. In the second K site, K(2) is bonded in a 7-coordinate geometry to one Mg(1), one O(5), one O(6), two equivalent O(1), and two equivalent O(2) atoms. The K(2)-Mg(1) bond length is 2.97 Å. The K(2)-O(5) bond length is 2.47 Å. The K(2)-O(6) bond length is 2.64 Å. Both K(2)-O(1) bond lengths are 2.96 Å. Both K(2)-O(2) bond lengths are 3.03 Å. Mg(1) is bonded in a 5-coordinate geometry to one K(2), one O(3), two equivalent O(1), and two equivalent O(4) atoms. The Mg(1)-O(3) bond length is 2.06 Å. Both Mg(1)-O(1) bond lengths are 1.99 Å. Both Mg(1)-O(4) bond lengths are 2.26 Å. Tb(1) is bonded to one O(2), one O(3), two equivalent O(1), and two equivalent O(4) atoms to form TbO6 octahedra that share corners with three equivalent V(1)O4 tetrahedra. The Tb(1)-O(2) bond length is 2.23 Å. The Tb(1)-O(3) bond length is 2.39 Å. Both Tb(1)-O(1) bond lengths are 2.49 Å. Both Tb(1)-O(4) bond lengths are 2.21 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 Tb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 20-51°. The V(1)-O(2) bond length is 1.83 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 in a rectangular see-saw-like geometry to one O(3), one O(5), and two equivalent O(4) atoms. The V(2)-O(3) bond length is 1.93 Å. The V(2)-O(5) bond length is 1.70 Å. Both V(2)-O(4) bond lengths are 1.86 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to one Rb(1), one K(1), one K(2), one Mg(1), one Tb(1), and one V(1) atom. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Rb(1), two equivalent K(2), one Tb(1), and one V(1) atom. In the third O site, O(3) is bonded to one Rb(1), two equivalent K(1), one Mg(1), one Tb(1), and one V(2) atom to form distorted corner-sharing OK2RbTbMgV octahedra. The corner-sharing octahedral tilt angles are 4°. In the fourth O site, O(4) is bonded in a distorted rectangular see-saw-like geometry to one K(1), one Mg(1), one Tb(1), and one V(2) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Rb(1), one K(2), and one V(2) atom. In the sixth O site, O(6) is bonded in a distorted single-bond geometry to two equivalent Rb(1), one K(1), one K(2), and one V(1) atom.