Na2OsO4 crystallizes in the hexagonal P-62m space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded to six equivalent O(1) atoms to form distorted NaO6 pentagonal pyramids that share corners with six equivalent Os(1)O6 octahedra, edges with three equivalent Os(1)O6 octahedra, and faces with two equivalent Na(1)O6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 10°. In the second Na site, Na(2) is bonded in a 9-coordinate geometry to three equivalent O(2) and six equivalent O(3) atoms. In the third Na site, Na(3) is bonded in a 7-coordinate geometry to one O(2), two equivalent O(1), and four equivalent O(3) atoms. Os(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form OsO6 octahedra that share corners with two equivalent Na(1)O6 pentagonal pyramids, edges with two equivalent Os(1)O6 octahedra, and  an edgeedge with one Na(1)O6 pentagonal pyramid. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Na(1), two equivalent Na(3), and two equivalent Os(1) atoms to form ONa4Os2 octahedra that share corners with four equivalent O(1)Na4Os2 octahedra, corners with four equivalent O(2)Na3Os2 trigonal bipyramids, edges with two equivalent O(1)Na4Os2 octahedra,  an edgeedge with one O(2)Na3Os2 trigonal bipyramid, and faces with two equivalent O(1)Na4Os2 octahedra. The corner-sharing octahedral tilt angles are 44°. In the second O site, O(2) is bonded to one Na(3), two equivalent Na(2), and two equivalent Os(1) atoms to form distorted ONa3Os2 trigonal bipyramids that share corners with four equivalent O(1)Na4Os2 octahedra, corners with six equivalent O(2)Na3Os2 trigonal bipyramids, and  an edgeedge with one O(1)Na4Os2 octahedra. The corner-sharing octahedral tilt angles range from 2-38°. In the third O site, O(3) is bonded in a 5-coordinate geometry to two equivalent Na(2), two equivalent Na(3), and one Os(1) atom.
Na2OsO4 crystallizes in the hexagonal P-62m space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded to six equivalent O(1) atoms to form distorted NaO6 pentagonal pyramids that share corners with six equivalent Os(1)O6 octahedra, edges with three equivalent Os(1)O6 octahedra, and faces with two equivalent Na(1)O6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 10°. All Na(1)-O(1) bond lengths are 2.41 Å. In the second Na site, Na(2) is bonded in a 9-coordinate geometry to three equivalent O(2) and six equivalent O(3) atoms. All Na(2)-O(2) bond lengths are 2.76 Å. All Na(2)-O(3) bond lengths are 2.48 Å. In the third Na site, Na(3) is bonded in a 7-coordinate geometry to one O(2), two equivalent O(1), and four equivalent O(3) atoms. The Na(3)-O(2) bond length is 2.24 Å. Both Na(3)-O(1) bond lengths are 2.54 Å. All Na(3)-O(3) bond lengths are 2.38 Å. Os(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form OsO6 octahedra that share corners with two equivalent Na(1)O6 pentagonal pyramids, edges with two equivalent Os(1)O6 octahedra, and  an edgeedge with one Na(1)O6 pentagonal pyramid. Both Os(1)-O(1) bond lengths are 2.05 Å. Both Os(1)-O(2) bond lengths are 2.00 Å. Both Os(1)-O(3) bond lengths are 1.79 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Na(1), two equivalent Na(3), and two equivalent Os(1) atoms to form ONa4Os2 octahedra that share corners with four equivalent O(1)Na4Os2 octahedra, corners with four equivalent O(2)Na3Os2 trigonal bipyramids, edges with two equivalent O(1)Na4Os2 octahedra,  an edgeedge with one O(2)Na3Os2 trigonal bipyramid, and faces with two equivalent O(1)Na4Os2 octahedra. The corner-sharing octahedral tilt angles are 44°. In the second O site, O(2) is bonded to one Na(3), two equivalent Na(2), and two equivalent Os(1) atoms to form distorted ONa3Os2 trigonal bipyramids that share corners with four equivalent O(1)Na4Os2 octahedra, corners with six equivalent O(2)Na3Os2 trigonal bipyramids, and  an edgeedge with one O(1)Na4Os2 octahedra. The corner-sharing octahedral tilt angles range from 2-38°. In the third O site, O(3) is bonded in a 5-coordinate geometry to two equivalent Na(2), two equivalent Na(3), and one Os(1) atom.