RbNaLi6(SiO4)2 crystallizes in the monoclinic C2/m space group. Rb(1) is bonded in a distorted body-centered cubic geometry to four equivalent O(1) and four equivalent O(2) atoms. Na(1) is bonded in a body-centered cubic geometry to two equivalent O(3), two equivalent O(4), two equivalent O(5), and two equivalent O(6) atoms. There are four inequivalent Li sites. In the first Li site, Li(1) is bonded to one O(5), one O(6), and two equivalent O(1) atoms to form LiO4 tetrahedra that share corners with two equivalent Si(1)O4 tetrahedra and corners with two equivalent Si(2)O4 tetrahedra. In the second Li site, Li(2) is bonded in a 4-coordinate geometry to one O(1), one O(2), one O(4), and one O(5) atom. In the third Li site, Li(3) is bonded in a 3-coordinate geometry to one O(1), one O(3), and one O(6) atom. In the fourth Li site, Li(4) is bonded to one O(3), one O(4), and two equivalent O(2) atoms to form LiO4 tetrahedra that share corners with two equivalent Si(1)O4 tetrahedra and corners with two equivalent Si(2)O4 tetrahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(3), one O(4), and two equivalent O(1) atoms to form SiO4 tetrahedra that share corners with two equivalent Li(1)O4 tetrahedra and corners with two equivalent Li(4)O4 tetrahedra. In the second Si site, Si(2) is bonded to one O(5), one O(6), and two equivalent O(2) atoms to form SiO4 tetrahedra that share corners with two equivalent Li(1)O4 tetrahedra and corners with two equivalent Li(4)O4 tetrahedra. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to two equivalent Rb(1), one Li(1), one Li(2), one Li(3), and one Si(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to two equivalent Rb(1), one Li(2), one Li(4), and one Si(2) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to two equivalent Na(1), one Li(4), two equivalent Li(3), and one Si(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to two equivalent Na(1), one Li(4), two equivalent Li(2), and one Si(1) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to two equivalent Na(1), one Li(1), two equivalent Li(2), and one Si(2) atom. In the sixth O site, O(6) is bonded in a 6-coordinate geometry to two equivalent Na(1), one Li(1), two equivalent Li(3), and one Si(2) atom.
RbNaLi6(SiO4)2 crystallizes in the monoclinic C2/m space group. Rb(1) is bonded in a distorted body-centered cubic geometry to four equivalent O(1) and four equivalent O(2) atoms. There are two shorter (2.97 Å) and two longer (3.10 Å) Rb(1)-O(1) bond lengths. There are two shorter (2.98 Å) and two longer (3.04 Å) Rb(1)-O(2) bond lengths. Na(1) is bonded in a body-centered cubic geometry to two equivalent O(3), two equivalent O(4), two equivalent O(5), and two equivalent O(6) atoms. Both Na(1)-O(3) bond lengths are 2.67 Å. Both Na(1)-O(4) bond lengths are 2.62 Å. Both Na(1)-O(5) bond lengths are 2.62 Å. Both Na(1)-O(6) bond lengths are 2.56 Å. There are four inequivalent Li sites. In the first Li site, Li(1) is bonded to one O(5), one O(6), and two equivalent O(1) atoms to form LiO4 tetrahedra that share corners with two equivalent Si(1)O4 tetrahedra and corners with two equivalent Si(2)O4 tetrahedra. The Li(1)-O(5) bond length is 1.96 Å. The Li(1)-O(6) bond length is 1.91 Å. Both Li(1)-O(1) bond lengths are 2.05 Å. In the second Li site, Li(2) is bonded in a 4-coordinate geometry to one O(1), one O(2), one O(4), and one O(5) atom. The Li(2)-O(1) bond length is 2.44 Å. The Li(2)-O(2) bond length is 1.93 Å. The Li(2)-O(4) bond length is 1.95 Å. The Li(2)-O(5) bond length is 1.92 Å. In the third Li site, Li(3) is bonded in a 3-coordinate geometry to one O(1), one O(3), and one O(6) atom. The Li(3)-O(1) bond length is 1.93 Å. The Li(3)-O(3) bond length is 1.94 Å. The Li(3)-O(6) bond length is 1.92 Å. In the fourth Li site, Li(4) is bonded to one O(3), one O(4), and two equivalent O(2) atoms to form LiO4 tetrahedra that share corners with two equivalent Si(1)O4 tetrahedra and corners with two equivalent Si(2)O4 tetrahedra. The Li(4)-O(3) bond length is 1.98 Å. The Li(4)-O(4) bond length is 1.93 Å. Both Li(4)-O(2) bond lengths are 2.04 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(3), one O(4), and two equivalent O(1) atoms to form SiO4 tetrahedra that share corners with two equivalent Li(1)O4 tetrahedra and corners with two equivalent Li(4)O4 tetrahedra. The Si(1)-O(3) bond length is 1.66 Å. The Si(1)-O(4) bond length is 1.66 Å. Both Si(1)-O(1) bond lengths are 1.66 Å. In the second Si site, Si(2) is bonded to one O(5), one O(6), and two equivalent O(2) atoms to form SiO4 tetrahedra that share corners with two equivalent Li(1)O4 tetrahedra and corners with two equivalent Li(4)O4 tetrahedra. The Si(2)-O(5) bond length is 1.66 Å. The Si(2)-O(6) bond length is 1.66 Å. Both Si(2)-O(2) bond lengths are 1.66 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to two equivalent Rb(1), one Li(1), one Li(2), one Li(3), and one Si(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to two equivalent Rb(1), one Li(2), one Li(4), and one Si(2) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to two equivalent Na(1), one Li(4), two equivalent Li(3), and one Si(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to two equivalent Na(1), one Li(4), two equivalent Li(2), and one Si(1) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to two equivalent Na(1), one Li(1), two equivalent Li(2), and one Si(2) atom. In the sixth O site, O(6) is bonded in a 6-coordinate geometry to two equivalent Na(1), one Li(1), two equivalent Li(3), and one Si(2) atom.