RbNaMg6O7 crystallizes in the tetragonal P4mm space group. Rb(1) is bonded in a 5-coordinate geometry to one O(1) and four equivalent O(5) atoms. Na(1) is bonded to one O(1) and four equivalent O(4) atoms to form NaO5 square pyramids that share corners with four equivalent Na(1)O5 square pyramids, edges with four equivalent Mg(1)O6 octahedra, and edges with four equivalent Mg(4)O6 octahedra. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one O(2), one O(3), and four equivalent O(4) atoms to form MgO6 octahedra that share corners with two equivalent Mg(2)O6 octahedra, corners with four equivalent Mg(1)O6 octahedra, edges with four equivalent Mg(4)O6 octahedra, and edges with four equivalent Na(1)O5 square pyramids. The corner-sharing octahedral tilt angles range from 0-6°. In the second Mg site, Mg(2) is bonded to one O(2), one O(3), and four equivalent O(5) atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles range from 0-6°. In the third Mg site, Mg(3) is bonded in a distorted square co-planar geometry to one O(4), one O(5), and two equivalent O(2) atoms. In the fourth Mg site, Mg(4) is bonded to one O(4), one O(5), two equivalent O(1), and two equivalent O(3) atoms to form MgO6 octahedra that share corners with four equivalent Mg(4)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Mg(2)O6 octahedra, edges with four equivalent Mg(4)O6 octahedra, and edges with two equivalent Na(1)O5 square pyramids. The corner-sharing octahedral tilt angles range from 3-4°. There are five inequivalent O sites. In the first O site, O(1) is bonded to one Rb(1), one Na(1), and four equivalent Mg(4) atoms to form ORbNaMg4 octahedra that share corners with four equivalent O(1)RbNaMg4 octahedra, edges with four equivalent O(3)Mg6 octahedra, edges with four equivalent O(4)Na2Mg4 octahedra, and edges with four equivalent O(5)Rb2Mg4 octahedra. The corner-sharing octahedral tilt angles are 4°. In the second O site, O(2) is bonded to one Mg(1), one Mg(2), and four equivalent Mg(3) atoms to form OMg6 octahedra that share corners with two equivalent O(3)Mg6 octahedra, corners with four equivalent O(2)Mg6 octahedra, edges with four equivalent O(4)Na2Mg4 octahedra, and edges with four equivalent O(5)Rb2Mg4 octahedra. The corner-sharing octahedral tilt angles range from 0-2°. In the third O site, O(3) is bonded to one Mg(1), one Mg(2), and four equivalent Mg(4) atoms to form OMg6 octahedra that share corners with two equivalent O(2)Mg6 octahedra, corners with four equivalent O(3)Mg6 octahedra, edges with four equivalent O(4)Na2Mg4 octahedra, edges with four equivalent O(5)Rb2Mg4 octahedra, and edges with four equivalent O(1)RbNaMg4 octahedra. The corner-sharing octahedral tilt angles range from 0-3°. In the fourth O site, O(4) is bonded to two equivalent Na(1), one Mg(3), one Mg(4), and two equivalent Mg(1) atoms to form ONa2Mg4 octahedra that share corners with two equivalent O(5)Rb2Mg4 octahedra, corners with four equivalent O(4)Na2Mg4 octahedra, edges with two equivalent O(2)Mg6 octahedra, edges with two equivalent O(3)Mg6 octahedra, edges with two equivalent O(1)RbNaMg4 octahedra, and edges with four equivalent O(4)Na2Mg4 octahedra. The corner-sharing octahedral tilt angles range from 0-10°. In the fifth O site, O(5) is bonded to two equivalent Rb(1), one Mg(3), one Mg(4), and two equivalent Mg(2) atoms to form ORb2Mg4 octahedra that share corners with two equivalent O(4)Na2Mg4 octahedra, corners with four equivalent O(5)Rb2Mg4 octahedra, edges with two equivalent O(2)Mg6 octahedra, edges with two equivalent O(3)Mg6 octahedra, edges with two equivalent O(1)RbNaMg4 octahedra, and edges with four equivalent O(5)Rb2Mg4 octahedra. The corner-sharing octahedral tilt angles range from 0-27°.
RbNaMg6O7 crystallizes in the tetragonal P4mm space group. Rb(1) is bonded in a 5-coordinate geometry to one O(1) and four equivalent O(5) atoms. The Rb(1)-O(1) bond length is 2.53 Å. All Rb(1)-O(5) bond lengths are 2.40 Å. Na(1) is bonded to one O(1) and four equivalent O(4) atoms to form NaO5 square pyramids that share corners with four equivalent Na(1)O5 square pyramids, edges with four equivalent Mg(1)O6 octahedra, and edges with four equivalent Mg(4)O6 octahedra. The Na(1)-O(1) bond length is 2.09 Å. All Na(1)-O(4) bond lengths are 2.35 Å. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one O(2), one O(3), and four equivalent O(4) atoms to form MgO6 octahedra that share corners with two equivalent Mg(2)O6 octahedra, corners with four equivalent Mg(1)O6 octahedra, edges with four equivalent Mg(4)O6 octahedra, and edges with four equivalent Na(1)O5 square pyramids. The corner-sharing octahedral tilt angles range from 0-6°. The Mg(1)-O(2) bond length is 2.08 Å. The Mg(1)-O(3) bond length is 2.01 Å. All Mg(1)-O(4) bond lengths are 2.34 Å. In the second Mg site, Mg(2) is bonded to one O(2), one O(3), and four equivalent O(5) atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles range from 0-6°. The Mg(2)-O(2) bond length is 2.07 Å. The Mg(2)-O(3) bond length is 2.01 Å. All Mg(2)-O(5) bond lengths are 2.34 Å. In the third Mg site, Mg(3) is bonded in a distorted square co-planar geometry to one O(4), one O(5), and two equivalent O(2) atoms. The Mg(3)-O(4) bond length is 1.91 Å. The Mg(3)-O(5) bond length is 1.99 Å. Both Mg(3)-O(2) bond lengths are 2.34 Å. In the fourth Mg site, Mg(4) is bonded to one O(4), one O(5), two equivalent O(1), and two equivalent O(3) atoms to form MgO6 octahedra that share corners with four equivalent Mg(4)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Mg(2)O6 octahedra, edges with four equivalent Mg(4)O6 octahedra, and edges with two equivalent Na(1)O5 square pyramids. The corner-sharing octahedral tilt angles range from 3-4°. The Mg(4)-O(4) bond length is 2.21 Å. The Mg(4)-O(5) bond length is 2.06 Å. Both Mg(4)-O(1) bond lengths are 2.34 Å. Both Mg(4)-O(3) bond lengths are 2.34 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded to one Rb(1), one Na(1), and four equivalent Mg(4) atoms to form ORbNaMg4 octahedra that share corners with four equivalent O(1)RbNaMg4 octahedra, edges with four equivalent O(3)Mg6 octahedra, edges with four equivalent O(4)Na2Mg4 octahedra, and edges with four equivalent O(5)Rb2Mg4 octahedra. The corner-sharing octahedral tilt angles are 4°. In the second O site, O(2) is bonded to one Mg(1), one Mg(2), and four equivalent Mg(3) atoms to form OMg6 octahedra that share corners with two equivalent O(3)Mg6 octahedra, corners with four equivalent O(2)Mg6 octahedra, edges with four equivalent O(4)Na2Mg4 octahedra, and edges with four equivalent O(5)Rb2Mg4 octahedra. The corner-sharing octahedral tilt angles range from 0-2°. In the third O site, O(3) is bonded to one Mg(1), one Mg(2), and four equivalent Mg(4) atoms to form OMg6 octahedra that share corners with two equivalent O(2)Mg6 octahedra, corners with four equivalent O(3)Mg6 octahedra, edges with four equivalent O(4)Na2Mg4 octahedra, edges with four equivalent O(5)Rb2Mg4 octahedra, and edges with four equivalent O(1)RbNaMg4 octahedra. The corner-sharing octahedral tilt angles range from 0-3°. In the fourth O site, O(4) is bonded to two equivalent Na(1), one Mg(3), one Mg(4), and two equivalent Mg(1) atoms to form ONa2Mg4 octahedra that share corners with two equivalent O(5)Rb2Mg4 octahedra, corners with four equivalent O(4)Na2Mg4 octahedra, edges with two equivalent O(2)Mg6 octahedra, edges with two equivalent O(3)Mg6 octahedra, edges with two equivalent O(1)RbNaMg4 octahedra, and edges with four equivalent O(4)Na2Mg4 octahedra. The corner-sharing octahedral tilt angles range from 0-10°. In the fifth O site, O(5) is bonded to two equivalent Rb(1), one Mg(3), one Mg(4), and two equivalent Mg(2) atoms to form ORb2Mg4 octahedra that share corners with two equivalent O(4)Na2Mg4 octahedra, corners with four equivalent O(5)Rb2Mg4 octahedra, edges with two equivalent O(2)Mg6 octahedra, edges with two equivalent O(3)Mg6 octahedra, edges with two equivalent O(1)RbNaMg4 octahedra, and edges with four equivalent O(5)Rb2Mg4 octahedra. The corner-sharing octahedral tilt angles range from 0-27°.