K5NaCe2(SO4)6 crystallizes in the monoclinic C2/m space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 9-coordinate geometry to one O(1), one O(5), one O(6), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. In the second K site, K(2) is bonded in a 8-coordinate geometry to four equivalent O(1) and four equivalent O(5) atoms. Na(1) is bonded to two equivalent O(6) and four equivalent O(1) atoms to form NaO6 octahedra that share corners with two equivalent S(1)O4 tetrahedra and corners with four equivalent S(2)O4 tetrahedra. Ce(1) is bonded in a 10-coordinate geometry to two equivalent O(2), two equivalent O(3), two equivalent O(4), two equivalent O(5), and two equivalent O(7) atoms. There are two inequivalent S sites. In the first S site, S(1) is bonded to one O(6), one O(7), and two equivalent O(2) atoms to form SO4 tetrahedra that share  a cornercorner with one Na(1)O6 octahedra. The corner-sharing octahedral tilt angles are 55°. In the second S site, S(2) is bonded to one O(1), one O(3), one O(4), and one O(5) atom to form SO4 tetrahedra that share  a cornercorner with one Na(1)O6 octahedra. The corner-sharing octahedral tilt angles are 43°. There are seven inequivalent O sites. In the first O site, O(4) is bonded in a distorted single-bond geometry to two equivalent K(1), one Ce(1), and one S(2) atom. In the second O site, O(5) is bonded in a distorted single-bond geometry to one K(1), one K(2), one Ce(1), and one S(2) atom. In the third O site, O(6) is bonded in a 4-coordinate geometry to two equivalent K(1), one Na(1), and one S(1) atom. In the fourth O site, O(7) is bonded in a single-bond geometry to two equivalent Ce(1) and one S(1) atom. In the fifth O site, O(1) is bonded in a 4-coordinate geometry to one K(1), one K(2), one Na(1), and one S(2) atom. In the sixth O site, O(2) is bonded in a distorted single-bond geometry to two equivalent K(1), one Ce(1), and one S(1) atom. In the seventh O site, O(3) is bonded in a 1-coordinate geometry to two equivalent K(1), one Ce(1), and one S(2) atom.
K5NaCe2(SO4)6 crystallizes in the monoclinic C2/m space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 9-coordinate geometry to one O(1), one O(5), one O(6), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. The K(1)-O(1) bond length is 2.73 Å. The K(1)-O(5) bond length is 2.77 Å. The K(1)-O(6) bond length is 2.81 Å. There is one shorter (2.78 Å) and one longer (3.00 Å) K(1)-O(2) bond length. There is one shorter (3.12 Å) and one longer (3.18 Å) K(1)-O(3) bond length. There is one shorter (2.83 Å) and one longer (2.91 Å) K(1)-O(4) bond length. In the second K site, K(2) is bonded in a 8-coordinate geometry to four equivalent O(1) and four equivalent O(5) atoms. All K(2)-O(1) bond lengths are 2.80 Å. All K(2)-O(5) bond lengths are 3.07 Å. Na(1) is bonded to two equivalent O(6) and four equivalent O(1) atoms to form NaO6 octahedra that share corners with two equivalent S(1)O4 tetrahedra and corners with four equivalent S(2)O4 tetrahedra. Both Na(1)-O(6) bond lengths are 2.48 Å. All Na(1)-O(1) bond lengths are 2.38 Å. Ce(1) is bonded in a 10-coordinate geometry to two equivalent O(2), two equivalent O(3), two equivalent O(4), two equivalent O(5), and two equivalent O(7) atoms. Both Ce(1)-O(2) bond lengths are 2.54 Å. Both Ce(1)-O(3) bond lengths are 2.51 Å. Both Ce(1)-O(4) bond lengths are 2.65 Å. Both Ce(1)-O(5) bond lengths are 2.68 Å. Both Ce(1)-O(7) bond lengths are 2.75 Å. There are two inequivalent S sites. In the first S site, S(1) is bonded to one O(6), one O(7), and two equivalent O(2) atoms to form SO4 tetrahedra that share  a cornercorner with one Na(1)O6 octahedra. The corner-sharing octahedral tilt angles are 55°. The S(1)-O(6) bond length is 1.47 Å. The S(1)-O(7) bond length is 1.51 Å. Both S(1)-O(2) bond lengths are 1.50 Å. In the second S site, S(2) is bonded to one O(1), one O(3), one O(4), and one O(5) atom to form SO4 tetrahedra that share  a cornercorner with one Na(1)O6 octahedra. The corner-sharing octahedral tilt angles are 43°. The S(2)-O(1) bond length is 1.48 Å. The S(2)-O(3) bond length is 1.50 Å. The S(2)-O(4) bond length is 1.50 Å. The S(2)-O(5) bond length is 1.50 Å. There are seven inequivalent O sites. In the first O site, O(4) is bonded in a distorted single-bond geometry to two equivalent K(1), one Ce(1), and one S(2) atom. In the second O site, O(5) is bonded in a distorted single-bond geometry to one K(1), one K(2), one Ce(1), and one S(2) atom. In the third O site, O(6) is bonded in a 4-coordinate geometry to two equivalent K(1), one Na(1), and one S(1) atom. In the fourth O site, O(7) is bonded in a single-bond geometry to two equivalent Ce(1) and one S(1) atom. In the fifth O site, O(1) is bonded in a 4-coordinate geometry to one K(1), one K(2), one Na(1), and one S(2) atom. In the sixth O site, O(2) is bonded in a distorted single-bond geometry to two equivalent K(1), one Ce(1), and one S(1) atom. In the seventh O site, O(3) is bonded in a 1-coordinate geometry to two equivalent K(1), one Ce(1), and one S(2) atom.