Na2CO6 crystallizes in the monoclinic Cc space group. There are four inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(1), one O(11), one O(12), one O(2), one O(6), and one O(7) atom to form distorted corner-sharing NaO6 octahedra. The corner-sharing octahedral tilt angles range from 54-55°. In the second Na site, Na(2) is bonded in a 4-coordinate geometry to one O(1), one O(11), one O(12), one O(2), one O(5), and one O(8) atom. In the third Na site, Na(3) is bonded to one O(10), one O(3), one O(4), one O(5), one O(8), and one O(9) atom to form edge-sharing NaO6 octahedra. In the fourth Na site, Na(4) is bonded to one O(10), one O(3), one O(4), one O(6), one O(7), and one O(9) atom to form a mixture of corner and edge-sharing NaO6 octahedra. The corner-sharing octahedral tilt angles range from 54-55°. There are two inequivalent C sites. In the first C site, C(1) is bonded in a trigonal planar geometry to one O(1), one O(3), and one O(9) atom. In the second C site, C(2) is bonded in a trigonal planar geometry to one O(10), one O(2), and one O(4) atom. There are twelve inequivalent O sites. In the first O site, O(5) is bonded in a trigonal non-coplanar geometry to one Na(2), one Na(3), and one O(7) atom. In the second O site, O(6) is bonded in a trigonal non-coplanar geometry to one Na(1), one Na(4), and one O(8) atom. In the third O site, O(7) is bonded in a trigonal planar geometry to one Na(1), one Na(4), and one O(5) atom. In the fourth O site, O(8) is bonded in a trigonal non-coplanar geometry to one Na(2), one Na(3), and one O(6) atom. In the fifth O site, O(9) is bonded in a distorted trigonal planar geometry to one Na(3), one Na(4), and one C(1) atom. In the sixth O site, O(10) is bonded in a distorted trigonal planar geometry to one Na(3), one Na(4), and one C(2) atom. In the seventh O site, O(11) is bonded in a 3-coordinate geometry to one Na(1), one Na(2), and one O(12) atom. In the eighth O site, O(12) is bonded in a 3-coordinate geometry to one Na(1), one Na(2), and one O(11) atom. In the ninth O site, O(1) is bonded in a distorted trigonal non-coplanar geometry to one Na(1), one Na(2), and one C(1) atom. In the tenth O site, O(2) is bonded in a distorted trigonal planar geometry to one Na(1), one Na(2), and one C(2) atom. In the eleventh O site, O(3) is bonded in a 3-coordinate geometry to one Na(3), one Na(4), and one C(1) atom. In the twelfth O site, O(4) is bonded in a 3-coordinate geometry to one Na(3), one Na(4), and one C(2) atom.
Na2CO6 crystallizes in the monoclinic Cc space group. There are four inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(1), one O(11), one O(12), one O(2), one O(6), and one O(7) atom to form distorted corner-sharing NaO6 octahedra. The corner-sharing octahedral tilt angles range from 54-55°. The Na(1)-O(1) bond length is 2.28 Å. The Na(1)-O(11) bond length is 2.55 Å. The Na(1)-O(12) bond length is 2.52 Å. The Na(1)-O(2) bond length is 2.28 Å. The Na(1)-O(6) bond length is 2.56 Å. The Na(1)-O(7) bond length is 2.54 Å. In the second Na site, Na(2) is bonded in a 4-coordinate geometry to one O(1), one O(11), one O(12), one O(2), one O(5), and one O(8) atom. The Na(2)-O(1) bond length is 2.27 Å. The Na(2)-O(11) bond length is 2.84 Å. The Na(2)-O(12) bond length is 2.82 Å. The Na(2)-O(2) bond length is 2.28 Å. The Na(2)-O(5) bond length is 2.50 Å. The Na(2)-O(8) bond length is 2.56 Å. In the third Na site, Na(3) is bonded to one O(10), one O(3), one O(4), one O(5), one O(8), and one O(9) atom to form edge-sharing NaO6 octahedra. The Na(3)-O(10) bond length is 2.39 Å. The Na(3)-O(3) bond length is 2.40 Å. The Na(3)-O(4) bond length is 2.40 Å. The Na(3)-O(5) bond length is 2.66 Å. The Na(3)-O(8) bond length is 2.70 Å. The Na(3)-O(9) bond length is 2.38 Å. In the fourth Na site, Na(4) is bonded to one O(10), one O(3), one O(4), one O(6), one O(7), and one O(9) atom to form a mixture of corner and edge-sharing NaO6 octahedra. The corner-sharing octahedral tilt angles range from 54-55°. The Na(4)-O(10) bond length is 2.37 Å. The Na(4)-O(3) bond length is 2.40 Å. The Na(4)-O(4) bond length is 2.41 Å. The Na(4)-O(6) bond length is 2.75 Å. The Na(4)-O(7) bond length is 2.63 Å. The Na(4)-O(9) bond length is 2.38 Å. There are two inequivalent C sites. In the first C site, C(1) is bonded in a trigonal planar geometry to one O(1), one O(3), and one O(9) atom. The C(1)-O(1) bond length is 1.30 Å. The C(1)-O(3) bond length is 1.29 Å. The C(1)-O(9) bond length is 1.29 Å. In the second C site, C(2) is bonded in a trigonal planar geometry to one O(10), one O(2), and one O(4) atom. The C(2)-O(10) bond length is 1.29 Å. The C(2)-O(2) bond length is 1.30 Å. The C(2)-O(4) bond length is 1.29 Å. There are twelve inequivalent O sites. In the first O site, O(5) is bonded in a trigonal non-coplanar geometry to one Na(2), one Na(3), and one O(7) atom. The O(5)-O(7) bond length is 1.27 Å. In the second O site, O(6) is bonded in a trigonal non-coplanar geometry to one Na(1), one Na(4), and one O(8) atom. The O(6)-O(8) bond length is 1.26 Å. In the third O site, O(7) is bonded in a trigonal planar geometry to one Na(1), one Na(4), and one O(5) atom. In the fourth O site, O(8) is bonded in a trigonal non-coplanar geometry to one Na(2), one Na(3), and one O(6) atom. In the fifth O site, O(9) is bonded in a distorted trigonal planar geometry to one Na(3), one Na(4), and one C(1) atom. In the sixth O site, O(10) is bonded in a distorted trigonal planar geometry to one Na(3), one Na(4), and one C(2) atom. In the seventh O site, O(11) is bonded in a 3-coordinate geometry to one Na(1), one Na(2), and one O(12) atom. The O(11)-O(12) bond length is 1.27 Å. In the eighth O site, O(12) is bonded in a 3-coordinate geometry to one Na(1), one Na(2), and one O(11) atom. In the ninth O site, O(1) is bonded in a distorted trigonal non-coplanar geometry to one Na(1), one Na(2), and one C(1) atom. In the tenth O site, O(2) is bonded in a distorted trigonal planar geometry to one Na(1), one Na(2), and one C(2) atom. In the eleventh O site, O(3) is bonded in a 3-coordinate geometry to one Na(3), one Na(4), and one C(1) atom. In the twelfth O site, O(4) is bonded in a 3-coordinate geometry to one Na(3), one Na(4), and one C(2) atom.