Na3H5(SeO4)4 crystallizes in the triclinic P-1 space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(1), one O(6), two equivalent O(2), and two equivalent O(5) atoms to form NaO6 octahedra that share  a cornercorner with one Na(2)O6 octahedra, corners with three equivalent Se(1)O4 tetrahedra, corners with three equivalent Se(2)O4 tetrahedra, and edges with two equivalent Na(1)O6 octahedra. The corner-sharing octahedral tilt angles are 71°. In the second Na site, Na(2) is bonded to two equivalent O(3), two equivalent O(6), and two equivalent O(7) atoms to form NaO6 octahedra that share corners with two equivalent Na(1)O6 octahedra, corners with two equivalent Se(1)O4 tetrahedra, and corners with four equivalent Se(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 71°. There are three inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(1) and one O(4) atom. In the second H site, H(2) is bonded in a linear geometry to two equivalent O(7) atoms. In the third H site, H(3) is bonded in a distorted linear geometry to one O(3) and one O(8) atom. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SeO4 tetrahedra that share  a cornercorner with one Na(2)O6 octahedra and corners with three equivalent Na(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 41-52°. In the second Se site, Se(2) is bonded to one O(5), one O(6), one O(7), and one O(8) atom to form SeO4 tetrahedra that share corners with two equivalent Na(2)O6 octahedra and corners with three equivalent Na(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 33-56°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Na(1), one H(1), and one Se(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to two equivalent Na(1) and one Se(1) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Na(2), one H(3), and one Se(1) atom. In the fourth O site, O(4) is bonded in a water-like geometry to one H(1) and one Se(1) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to two equivalent Na(1) and one Se(2) atom. In the sixth O site, O(6) is bonded in a trigonal planar geometry to one Na(1), one Na(2), and one Se(2) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Na(2), one H(2), and one Se(2) atom. In the eighth O site, O(8) is bonded in a water-like geometry to one H(3) and one Se(2) atom.
Na3H5(SeO4)4 crystallizes in the triclinic P-1 space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(1), one O(6), two equivalent O(2), and two equivalent O(5) atoms to form NaO6 octahedra that share  a cornercorner with one Na(2)O6 octahedra, corners with three equivalent Se(1)O4 tetrahedra, corners with three equivalent Se(2)O4 tetrahedra, and edges with two equivalent Na(1)O6 octahedra. The corner-sharing octahedral tilt angles are 71°. The Na(1)-O(1) bond length is 2.43 Å. The Na(1)-O(6) bond length is 2.48 Å. There is one shorter (2.43 Å) and one longer (2.44 Å) Na(1)-O(2) bond length. There is one shorter (2.46 Å) and one longer (2.51 Å) Na(1)-O(5) bond length. In the second Na site, Na(2) is bonded to two equivalent O(3), two equivalent O(6), and two equivalent O(7) atoms to form NaO6 octahedra that share corners with two equivalent Na(1)O6 octahedra, corners with two equivalent Se(1)O4 tetrahedra, and corners with four equivalent Se(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 71°. Both Na(2)-O(3) bond lengths are 2.44 Å. Both Na(2)-O(6) bond lengths are 2.44 Å. Both Na(2)-O(7) bond lengths are 2.58 Å. There are three inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(1) and one O(4) atom. The H(1)-O(1) bond length is 1.72 Å. The H(1)-O(4) bond length is 1.01 Å. In the second H site, H(2) is bonded in a linear geometry to two equivalent O(7) atoms. Both H(2)-O(7) bond lengths are 1.21 Å. In the third H site, H(3) is bonded in a distorted linear geometry to one O(3) and one O(8) atom. The H(3)-O(3) bond length is 1.62 Å. The H(3)-O(8) bond length is 1.02 Å. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SeO4 tetrahedra that share  a cornercorner with one Na(2)O6 octahedra and corners with three equivalent Na(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 41-52°. The Se(1)-O(1) bond length is 1.66 Å. The Se(1)-O(2) bond length is 1.65 Å. The Se(1)-O(3) bond length is 1.66 Å. The Se(1)-O(4) bond length is 1.76 Å. In the second Se site, Se(2) is bonded to one O(5), one O(6), one O(7), and one O(8) atom to form SeO4 tetrahedra that share corners with two equivalent Na(2)O6 octahedra and corners with three equivalent Na(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 33-56°. The Se(2)-O(5) bond length is 1.64 Å. The Se(2)-O(6) bond length is 1.65 Å. The Se(2)-O(7) bond length is 1.70 Å. The Se(2)-O(8) bond length is 1.74 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Na(1), one H(1), and one Se(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to two equivalent Na(1) and one Se(1) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Na(2), one H(3), and one Se(1) atom. In the fourth O site, O(4) is bonded in a water-like geometry to one H(1) and one Se(1) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to two equivalent Na(1) and one Se(2) atom. In the sixth O site, O(6) is bonded in a trigonal planar geometry to one Na(1), one Na(2), and one Se(2) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Na(2), one H(2), and one Se(2) atom. In the eighth O site, O(8) is bonded in a water-like geometry to one H(3) and one Se(2) atom.