Na6Sn2O7 crystallizes in the monoclinic C2/c space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(2), one O(3), one O(4), and two equivalent O(1) atoms to form distorted NaO5 square pyramids that share  a cornercorner with one Na(1)O5 square pyramid,  a cornercorner with one Sn(1)O5 square pyramid, corners with three equivalent Na(2)O5 square pyramids, corners with five equivalent Na(3)O5 square pyramids,  an edgeedge with one Na(1)O5 square pyramid,  an edgeedge with one Na(3)O5 square pyramid, edges with two equivalent Na(2)O5 square pyramids, and edges with three equivalent Sn(1)O5 square pyramids. In the second Na site, Na(2) is bonded to one O(1), one O(3), one O(4), and two equivalent O(2) atoms to form distorted NaO5 square pyramids that share  a cornercorner with one Na(2)O5 square pyramid, corners with two equivalent Na(3)O5 square pyramids, corners with three equivalent Na(1)O5 square pyramids, corners with four equivalent Sn(1)O5 square pyramids,  an edgeedge with one Na(2)O5 square pyramid, edges with two equivalent Na(1)O5 square pyramids, edges with two equivalent Na(3)O5 square pyramids, and edges with two equivalent Sn(1)O5 square pyramids. In the third Na site, Na(3) is bonded to one O(2), two equivalent O(1), and two equivalent O(3) atoms to form NaO5 square pyramids that share corners with two equivalent Na(2)O5 square pyramids, corners with two equivalent Na(3)O5 square pyramids, corners with two equivalent Sn(1)O5 square pyramids, corners with five equivalent Na(1)O5 square pyramids,  an edgeedge with one Na(1)O5 square pyramid,  an edgeedge with one Na(3)O5 square pyramid, edges with two equivalent Na(2)O5 square pyramids, and edges with two equivalent Sn(1)O5 square pyramids. Sn(1) is bonded to one O(1), one O(3), one O(4), and two equivalent O(2) atoms to form distorted SnO5 square pyramids that share  a cornercorner with one Na(1)O5 square pyramid,  a cornercorner with one Sn(1)O5 square pyramid, corners with two equivalent Na(3)O5 square pyramids, corners with four equivalent Na(2)O5 square pyramids,  an edgeedge with one Sn(1)O5 square pyramid, edges with two equivalent Na(2)O5 square pyramids, edges with two equivalent Na(3)O5 square pyramids, and edges with three equivalent Na(1)O5 square pyramids. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Na(2), two equivalent Na(1), two equivalent Na(3), and one Sn(1) atom to form distorted ONa5Sn octahedra that share corners with four equivalent O(3)Na4Sn square pyramids, edges with two equivalent O(4)Na4Sn2 octahedra, edges with two equivalent O(1)Na5Sn octahedra, edges with four equivalent O(2)Na4Sn2 octahedra, and edges with two equivalent O(3)Na4Sn square pyramids. In the second O site, O(2) is bonded to one Na(1), one Na(3), two equivalent Na(2), and two equivalent Sn(1) atoms to form ONa4Sn2 octahedra that share corners with three equivalent O(4)Na4Sn2 octahedra, corners with three equivalent O(3)Na4Sn square pyramids,  an edgeedge with one O(4)Na4Sn2 octahedra, edges with two equivalent O(2)Na4Sn2 octahedra, edges with four equivalent O(1)Na5Sn octahedra, and edges with two equivalent O(3)Na4Sn square pyramids. The corner-sharing octahedral tilt angles range from 1-21°. In the third O site, O(3) is bonded to one Na(1), one Na(2), two equivalent Na(3), and one Sn(1) atom to form distorted ONa4Sn square pyramids that share  a cornercorner with one O(4)Na4Sn2 octahedra, corners with three equivalent O(2)Na4Sn2 octahedra, corners with four equivalent O(1)Na5Sn octahedra, corners with two equivalent O(3)Na4Sn square pyramids,  an edgeedge with one O(4)Na4Sn2 octahedra, edges with two equivalent O(2)Na4Sn2 octahedra, and edges with two equivalent O(1)Na5Sn octahedra. The corner-sharing octahedral tilt angles range from 9-93°. In the fourth O site, O(4) is bonded to two equivalent Na(1), two equivalent Na(2), and two equivalent Sn(1) atoms to form ONa4Sn2 octahedra that share corners with six equivalent O(2)Na4Sn2 octahedra, corners with two equivalent O(3)Na4Sn square pyramids, edges with two equivalent O(2)Na4Sn2 octahedra, edges with four equivalent O(1)Na5Sn octahedra, and edges with two equivalent O(3)Na4Sn square pyramids. The corner-sharing octahedral tilt angles range from 1-21°.
Na6Sn2O7 crystallizes in the monoclinic C2/c space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(2), one O(3), one O(4), and two equivalent O(1) atoms to form distorted NaO5 square pyramids that share  a cornercorner with one Na(1)O5 square pyramid,  a cornercorner with one Sn(1)O5 square pyramid, corners with three equivalent Na(2)O5 square pyramids, corners with five equivalent Na(3)O5 square pyramids,  an edgeedge with one Na(1)O5 square pyramid,  an edgeedge with one Na(3)O5 square pyramid, edges with two equivalent Na(2)O5 square pyramids, and edges with three equivalent Sn(1)O5 square pyramids. The Na(1)-O(2) bond length is 2.41 Å. The Na(1)-O(3) bond length is 2.34 Å. The Na(1)-O(4) bond length is 2.47 Å. There is one shorter (2.27 Å) and one longer (2.43 Å) Na(1)-O(1) bond length. In the second Na site, Na(2) is bonded to one O(1), one O(3), one O(4), and two equivalent O(2) atoms to form distorted NaO5 square pyramids that share  a cornercorner with one Na(2)O5 square pyramid, corners with two equivalent Na(3)O5 square pyramids, corners with three equivalent Na(1)O5 square pyramids, corners with four equivalent Sn(1)O5 square pyramids,  an edgeedge with one Na(2)O5 square pyramid, edges with two equivalent Na(1)O5 square pyramids, edges with two equivalent Na(3)O5 square pyramids, and edges with two equivalent Sn(1)O5 square pyramids. The Na(2)-O(1) bond length is 2.48 Å. The Na(2)-O(3) bond length is 2.32 Å. The Na(2)-O(4) bond length is 2.41 Å. There is one shorter (2.38 Å) and one longer (2.45 Å) Na(2)-O(2) bond length. In the third Na site, Na(3) is bonded to one O(2), two equivalent O(1), and two equivalent O(3) atoms to form NaO5 square pyramids that share corners with two equivalent Na(2)O5 square pyramids, corners with two equivalent Na(3)O5 square pyramids, corners with two equivalent Sn(1)O5 square pyramids, corners with five equivalent Na(1)O5 square pyramids,  an edgeedge with one Na(1)O5 square pyramid,  an edgeedge with one Na(3)O5 square pyramid, edges with two equivalent Na(2)O5 square pyramids, and edges with two equivalent Sn(1)O5 square pyramids. The Na(3)-O(2) bond length is 2.41 Å. There is one shorter (2.27 Å) and one longer (2.36 Å) Na(3)-O(1) bond length. There is one shorter (2.32 Å) and one longer (2.40 Å) Na(3)-O(3) bond length. Sn(1) is bonded to one O(1), one O(3), one O(4), and two equivalent O(2) atoms to form distorted SnO5 square pyramids that share  a cornercorner with one Na(1)O5 square pyramid,  a cornercorner with one Sn(1)O5 square pyramid, corners with two equivalent Na(3)O5 square pyramids, corners with four equivalent Na(2)O5 square pyramids,  an edgeedge with one Sn(1)O5 square pyramid, edges with two equivalent Na(2)O5 square pyramids, edges with two equivalent Na(3)O5 square pyramids, and edges with three equivalent Na(1)O5 square pyramids. The Sn(1)-O(1) bond length is 2.01 Å. The Sn(1)-O(3) bond length is 2.03 Å. The Sn(1)-O(4) bond length is 2.20 Å. There is one shorter (2.12 Å) and one longer (2.22 Å) Sn(1)-O(2) bond length. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Na(2), two equivalent Na(1), two equivalent Na(3), and one Sn(1) atom to form distorted ONa5Sn octahedra that share corners with four equivalent O(3)Na4Sn square pyramids, edges with two equivalent O(4)Na4Sn2 octahedra, edges with two equivalent O(1)Na5Sn octahedra, edges with four equivalent O(2)Na4Sn2 octahedra, and edges with two equivalent O(3)Na4Sn square pyramids. In the second O site, O(2) is bonded to one Na(1), one Na(3), two equivalent Na(2), and two equivalent Sn(1) atoms to form ONa4Sn2 octahedra that share corners with three equivalent O(4)Na4Sn2 octahedra, corners with three equivalent O(3)Na4Sn square pyramids,  an edgeedge with one O(4)Na4Sn2 octahedra, edges with two equivalent O(2)Na4Sn2 octahedra, edges with four equivalent O(1)Na5Sn octahedra, and edges with two equivalent O(3)Na4Sn square pyramids. The corner-sharing octahedral tilt angles range from 1-21°. In the third O site, O(3) is bonded to one Na(1), one Na(2), two equivalent Na(3), and one Sn(1) atom to form distorted ONa4Sn square pyramids that share  a cornercorner with one O(4)Na4Sn2 octahedra, corners with three equivalent O(2)Na4Sn2 octahedra, corners with four equivalent O(1)Na5Sn octahedra, corners with two equivalent O(3)Na4Sn square pyramids,  an edgeedge with one O(4)Na4Sn2 octahedra, edges with two equivalent O(2)Na4Sn2 octahedra, and edges with two equivalent O(1)Na5Sn octahedra. The corner-sharing octahedral tilt angles range from 9-93°. In the fourth O site, O(4) is bonded to two equivalent Na(1), two equivalent Na(2), and two equivalent Sn(1) atoms to form ONa4Sn2 octahedra that share corners with six equivalent O(2)Na4Sn2 octahedra, corners with two equivalent O(3)Na4Sn square pyramids, edges with two equivalent O(2)Na4Sn2 octahedra, edges with four equivalent O(1)Na5Sn octahedra, and edges with two equivalent O(3)Na4Sn square pyramids. The corner-sharing octahedral tilt angles range from 1-21°.