Na3OsH7 crystallizes in the tetragonal P4_2/mnm space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 8-coordinate geometry to one H(4), two equivalent H(1), two equivalent H(2), and three equivalent H(3) atoms. In the second Na site, Na(2) is bonded in a 6-coordinate geometry to two equivalent H(2), two equivalent H(3), and four equivalent H(1) atoms. Os(1) is bonded in a pentagonal bipyramidal geometry to one H(4), two equivalent H(1), two equivalent H(2), and two equivalent H(3) atoms. There are four inequivalent H sites. In the first H site, H(4) is bonded in a 3-coordinate geometry to two equivalent Na(1) and one Os(1) atom. In the second H site, H(1) is bonded to two equivalent Na(1), two equivalent Na(2), and one Os(1) atom to form distorted HNa4Os square pyramids that share corners with five equivalent H(2)Na3Os tetrahedra, edges with three equivalent H(1)Na4Os square pyramids,  an edgeedge with one H(2)Na3Os tetrahedra,  a faceface with one H(1)Na4Os square pyramid, and  a faceface with one H(2)Na3Os tetrahedra. In the third H site, H(2) is bonded to one Na(2), two equivalent Na(1), and one Os(1) atom to form distorted HNa3Os tetrahedra that share corners with five equivalent H(1)Na4Os square pyramids,  a cornercorner with one H(2)Na3Os tetrahedra,  an edgeedge with one H(1)Na4Os square pyramid,  a faceface with one H(1)Na4Os square pyramid, and  a faceface with one H(2)Na3Os tetrahedra. In the fourth H site, H(3) is bonded in a 5-coordinate geometry to one Na(2), three equivalent Na(1), and one Os(1) atom.
Na3OsH7 crystallizes in the tetragonal P4_2/mnm space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 8-coordinate geometry to one H(4), two equivalent H(1), two equivalent H(2), and three equivalent H(3) atoms. The Na(1)-H(4) bond length is 2.31 Å. Both Na(1)-H(1) bond lengths are 2.53 Å. Both Na(1)-H(2) bond lengths are 2.30 Å. There is one shorter (2.34 Å) and two longer (2.65 Å) Na(1)-H(3) bond lengths. In the second Na site, Na(2) is bonded in a 6-coordinate geometry to two equivalent H(2), two equivalent H(3), and four equivalent H(1) atoms. Both Na(2)-H(2) bond lengths are 2.17 Å. Both Na(2)-H(3) bond lengths are 2.65 Å. All Na(2)-H(1) bond lengths are 2.34 Å. Os(1) is bonded in a pentagonal bipyramidal geometry to one H(4), two equivalent H(1), two equivalent H(2), and two equivalent H(3) atoms. The Os(1)-H(4) bond length is 1.67 Å. Both Os(1)-H(1) bond lengths are 1.68 Å. Both Os(1)-H(2) bond lengths are 1.65 Å. Both Os(1)-H(3) bond lengths are 1.73 Å. There are four inequivalent H sites. In the first H site, H(4) is bonded in a 3-coordinate geometry to two equivalent Na(1) and one Os(1) atom. In the second H site, H(1) is bonded to two equivalent Na(1), two equivalent Na(2), and one Os(1) atom to form distorted HNa4Os square pyramids that share corners with five equivalent H(2)Na3Os tetrahedra, edges with three equivalent H(1)Na4Os square pyramids,  an edgeedge with one H(2)Na3Os tetrahedra,  a faceface with one H(1)Na4Os square pyramid, and  a faceface with one H(2)Na3Os tetrahedra. In the third H site, H(2) is bonded to one Na(2), two equivalent Na(1), and one Os(1) atom to form distorted HNa3Os tetrahedra that share corners with five equivalent H(1)Na4Os square pyramids,  a cornercorner with one H(2)Na3Os tetrahedra,  an edgeedge with one H(1)Na4Os square pyramid,  a faceface with one H(1)Na4Os square pyramid, and  a faceface with one H(2)Na3Os tetrahedra. In the fourth H site, H(3) is bonded in a 5-coordinate geometry to one Na(2), three equivalent Na(1), and one Os(1) atom.