Na5H7(Se2O9)2 crystallizes in the triclinic P1 space group. There are five inequivalent Na sites. In the first Na site, Na(1) is bonded in a 7-coordinate geometry to one O(1), one O(11), one O(14), one O(17), one O(6), one O(8), and one O(9) atom. In the second Na site, Na(2) is bonded to one O(10), one O(12), one O(13), one O(18), one O(2), one O(5), and one O(7) atom to form distorted NaO7 pentagonal bipyramids that share  a cornercorner with one Se(2)O4 tetrahedra,  a cornercorner with one Se(4)O4 tetrahedra, corners with two equivalent Se(1)O4 tetrahedra,  an edgeedge with one Na(3)O6 octahedra,  an edgeedge with one Na(4)O6 octahedra,  an edgeedge with one Na(5)O6 octahedra, and  an edgeedge with one Se(4)O4 tetrahedra. In the third Na site, Na(3) is bonded to one O(3), one O(4), one O(5), one O(6), one O(7), and one O(8) atom to form distorted NaO6 octahedra that share corners with two equivalent Se(1)O4 tetrahedra, corners with two equivalent Se(2)O4 tetrahedra,  an edgeedge with one Na(4)O6 octahedra,  an edgeedge with one Na(5)O6 octahedra, and  an edgeedge with one Na(2)O7 pentagonal bipyramid. In the fourth Na site, Na(4) is bonded to one O(10), one O(12), one O(15), one O(4), one O(8), and one O(9) atom to form NaO6 octahedra that share corners with two equivalent Se(2)O4 tetrahedra, corners with two equivalent Se(3)O4 tetrahedra, corners with two equivalent Se(4)O4 tetrahedra,  an edgeedge with one Na(3)O6 octahedra,  an edgeedge with one Na(5)O6 octahedra, and  an edgeedge with one Na(2)O7 pentagonal bipyramid. In the fifth Na site, Na(5) is bonded to one O(10), one O(11), one O(16), one O(3), one O(7), and one O(9) atom to form NaO6 octahedra that share corners with two equivalent Se(1)O4 tetrahedra, corners with two equivalent Se(3)O4 tetrahedra, corners with two equivalent Se(4)O4 tetrahedra,  an edgeedge with one Na(3)O6 octahedra,  an edgeedge with one Na(4)O6 octahedra, and  an edgeedge with one Na(2)O7 pentagonal bipyramid. There are seven inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(5) atom. In the second H site, H(2) is bonded in a single-bond geometry to one O(6) atom. In the third H site, H(3) is bonded in a single-bond geometry to one O(5) atom. In the fourth H site, H(4) is bonded in a single-bond geometry to one O(6) atom. In the fifth H site, H(5) is bonded in a distorted linear geometry to one O(13) and one O(15) atom. In the sixth H site, H(6) is bonded in a distorted linear geometry to one O(14) and one O(16) atom. In the seventh H site, H(7) is bonded in a linear geometry to one O(11) and one O(12) atom. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded to one O(1), one O(13), one O(3), and one O(7) atom to form SeO4 tetrahedra that share corners with two equivalent Na(3)O6 octahedra, corners with two equivalent Na(5)O6 octahedra, and corners with two equivalent Na(2)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 42-75°. In the second Se site, Se(2) is bonded to one O(14), one O(2), one O(4), and one O(8) atom to form SeO4 tetrahedra that share corners with two equivalent Na(3)O6 octahedra, corners with two equivalent Na(4)O6 octahedra, and  a cornercorner with one Na(2)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles range from 42-75°. In the third Se site, Se(3) is bonded to one O(11), one O(15), one O(17), and one O(9) atom to form SeO4 tetrahedra that share corners with two equivalent Na(4)O6 octahedra and corners with two equivalent Na(5)O6 octahedra. The corner-sharing octahedral tilt angles range from 40-61°. In the fourth Se site, Se(4) is bonded to one O(10), one O(12), one O(16), and one O(18) atom to form SeO4 tetrahedra that share corners with two equivalent Na(4)O6 octahedra, corners with two equivalent Na(5)O6 octahedra,  a cornercorner with one Na(2)O7 pentagonal bipyramid, and  an edgeedge with one Na(2)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles range from 41-59°. There are eighteen inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Na(1) and one Se(1) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Na(2) and one Se(2) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Na(3), one Na(5), and one Se(1) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Na(3), one Na(4), and one Se(2) atom. In the fifth O site, O(5) is bonded in a distorted water-like geometry to one Na(2), one Na(3), one H(1), and one H(3) atom. In the sixth O site, O(6) is bonded in a distorted water-like geometry to one Na(1), one Na(3), one H(2), and one H(4) atom. In the seventh O site, O(7) is bonded in a distorted rectangular see-saw-like geometry to one Na(2), one Na(3), one Na(5), and one Se(1) atom. In the eighth O site, O(8) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), one Na(3), one Na(4), and one Se(2) atom. In the ninth O site, O(9) is bonded in a 4-coordinate geometry to one Na(1), one Na(4), one Na(5), and one Se(3) atom. In the tenth O site, O(10) is bonded in a 4-coordinate geometry to one Na(2), one Na(4), one Na(5), and one Se(4) atom. In the eleventh O site, O(11) is bonded in a 4-coordinate geometry to one Na(1), one Na(5), one H(7), and one Se(3) atom. In the twelfth O site, O(12) is bonded in a 4-coordinate geometry to one Na(2), one Na(4), one H(7), and one Se(4) atom. In the thirteenth O site, O(13) is bonded in a 3-coordinate geometry to one Na(2), one H(5), and one Se(1) atom. In the fourteenth O site, O(14) is bonded in a 3-coordinate geometry to one Na(1), one H(6), and one Se(2) atom. In the fifteenth O site, O(15) is bonded in a distorted trigonal planar geometry to one Na(4), one H(5), and one Se(3) atom. In the sixteenth O site, O(16) is bonded in a distorted trigonal planar geometry to one Na(5), one H(6), and one Se(4) atom. In the seventeenth O site, O(17) is bonded in a water-like geometry to one Na(1) and one Se(3) atom. In the eighteenth O site, O(18) is bonded in a distorted water-like geometry to one Na(2) and one Se(4) atom.
Na5H7(Se2O9)2 crystallizes in the triclinic P1 space group. There are five inequivalent Na sites. In the first Na site, Na(1) is bonded in a 7-coordinate geometry to one O(1), one O(11), one O(14), one O(17), one O(6), one O(8), and one O(9) atom. The Na(1)-O(1) bond length is 2.42 Å. The Na(1)-O(11) bond length is 2.84 Å. The Na(1)-O(14) bond length is 2.64 Å. The Na(1)-O(17) bond length is 2.47 Å. The Na(1)-O(6) bond length is 2.36 Å. The Na(1)-O(8) bond length is 2.47 Å. The Na(1)-O(9) bond length is 2.83 Å. In the second Na site, Na(2) is bonded to one O(10), one O(12), one O(13), one O(18), one O(2), one O(5), and one O(7) atom to form distorted NaO7 pentagonal bipyramids that share  a cornercorner with one Se(2)O4 tetrahedra,  a cornercorner with one Se(4)O4 tetrahedra, corners with two equivalent Se(1)O4 tetrahedra,  an edgeedge with one Na(3)O6 octahedra,  an edgeedge with one Na(4)O6 octahedra,  an edgeedge with one Na(5)O6 octahedra, and  an edgeedge with one Se(4)O4 tetrahedra. The Na(2)-O(10) bond length is 2.80 Å. The Na(2)-O(12) bond length is 2.75 Å. The Na(2)-O(13) bond length is 2.62 Å. The Na(2)-O(18) bond length is 2.50 Å. The Na(2)-O(2) bond length is 2.45 Å. The Na(2)-O(5) bond length is 2.37 Å. The Na(2)-O(7) bond length is 2.47 Å. In the third Na site, Na(3) is bonded to one O(3), one O(4), one O(5), one O(6), one O(7), and one O(8) atom to form distorted NaO6 octahedra that share corners with two equivalent Se(1)O4 tetrahedra, corners with two equivalent Se(2)O4 tetrahedra,  an edgeedge with one Na(4)O6 octahedra,  an edgeedge with one Na(5)O6 octahedra, and  an edgeedge with one Na(2)O7 pentagonal bipyramid. The Na(3)-O(3) bond length is 2.52 Å. The Na(3)-O(4) bond length is 2.53 Å. The Na(3)-O(5) bond length is 2.30 Å. The Na(3)-O(6) bond length is 2.31 Å. The Na(3)-O(7) bond length is 2.82 Å. The Na(3)-O(8) bond length is 2.83 Å. In the fourth Na site, Na(4) is bonded to one O(10), one O(12), one O(15), one O(4), one O(8), and one O(9) atom to form NaO6 octahedra that share corners with two equivalent Se(2)O4 tetrahedra, corners with two equivalent Se(3)O4 tetrahedra, corners with two equivalent Se(4)O4 tetrahedra,  an edgeedge with one Na(3)O6 octahedra,  an edgeedge with one Na(5)O6 octahedra, and  an edgeedge with one Na(2)O7 pentagonal bipyramid. The Na(4)-O(10) bond length is 2.49 Å. The Na(4)-O(12) bond length is 2.48 Å. The Na(4)-O(15) bond length is 2.45 Å. The Na(4)-O(4) bond length is 2.42 Å. The Na(4)-O(8) bond length is 2.43 Å. The Na(4)-O(9) bond length is 2.60 Å. In the fifth Na site, Na(5) is bonded to one O(10), one O(11), one O(16), one O(3), one O(7), and one O(9) atom to form NaO6 octahedra that share corners with two equivalent Se(1)O4 tetrahedra, corners with two equivalent Se(3)O4 tetrahedra, corners with two equivalent Se(4)O4 tetrahedra,  an edgeedge with one Na(3)O6 octahedra,  an edgeedge with one Na(4)O6 octahedra, and  an edgeedge with one Na(2)O7 pentagonal bipyramid. The Na(5)-O(10) bond length is 2.63 Å. The Na(5)-O(11) bond length is 2.48 Å. The Na(5)-O(16) bond length is 2.44 Å. The Na(5)-O(3) bond length is 2.41 Å. The Na(5)-O(7) bond length is 2.39 Å. The Na(5)-O(9) bond length is 2.51 Å. There are seven inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(5) atom. The H(1)-O(5) bond length is 0.99 Å. In the second H site, H(2) is bonded in a single-bond geometry to one O(6) atom. The H(2)-O(6) bond length is 0.99 Å. In the third H site, H(3) is bonded in a single-bond geometry to one O(5) atom. The H(3)-O(5) bond length is 0.98 Å. In the fourth H site, H(4) is bonded in a single-bond geometry to one O(6) atom. The H(4)-O(6) bond length is 0.98 Å. In the fifth H site, H(5) is bonded in a distorted linear geometry to one O(13) and one O(15) atom. The H(5)-O(13) bond length is 1.02 Å. The H(5)-O(15) bond length is 1.61 Å. In the sixth H site, H(6) is bonded in a distorted linear geometry to one O(14) and one O(16) atom. The H(6)-O(14) bond length is 1.03 Å. The H(6)-O(16) bond length is 1.58 Å. In the seventh H site, H(7) is bonded in a linear geometry to one O(11) and one O(12) atom. The H(7)-O(11) bond length is 1.12 Å. The H(7)-O(12) bond length is 1.34 Å. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded to one O(1), one O(13), one O(3), and one O(7) atom to form SeO4 tetrahedra that share corners with two equivalent Na(3)O6 octahedra, corners with two equivalent Na(5)O6 octahedra, and corners with two equivalent Na(2)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 42-75°. The Se(1)-O(1) bond length is 1.64 Å. The Se(1)-O(13) bond length is 1.78 Å. The Se(1)-O(3) bond length is 1.65 Å. The Se(1)-O(7) bond length is 1.67 Å. In the second Se site, Se(2) is bonded to one O(14), one O(2), one O(4), and one O(8) atom to form SeO4 tetrahedra that share corners with two equivalent Na(3)O6 octahedra, corners with two equivalent Na(4)O6 octahedra, and  a cornercorner with one Na(2)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles range from 42-75°. The Se(2)-O(14) bond length is 1.77 Å. The Se(2)-O(2) bond length is 1.64 Å. The Se(2)-O(4) bond length is 1.66 Å. The Se(2)-O(8) bond length is 1.67 Å. In the third Se site, Se(3) is bonded to one O(11), one O(15), one O(17), and one O(9) atom to form SeO4 tetrahedra that share corners with two equivalent Na(4)O6 octahedra and corners with two equivalent Na(5)O6 octahedra. The corner-sharing octahedral tilt angles range from 40-61°. The Se(3)-O(11) bond length is 1.75 Å. The Se(3)-O(15) bond length is 1.66 Å. The Se(3)-O(17) bond length is 1.66 Å. The Se(3)-O(9) bond length is 1.66 Å. In the fourth Se site, Se(4) is bonded to one O(10), one O(12), one O(16), and one O(18) atom to form SeO4 tetrahedra that share corners with two equivalent Na(4)O6 octahedra, corners with two equivalent Na(5)O6 octahedra,  a cornercorner with one Na(2)O7 pentagonal bipyramid, and  an edgeedge with one Na(2)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles range from 41-59°. The Se(4)-O(10) bond length is 1.67 Å. The Se(4)-O(12) bond length is 1.71 Å. The Se(4)-O(16) bond length is 1.67 Å. The Se(4)-O(18) bond length is 1.67 Å. There are eighteen inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Na(1) and one Se(1) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Na(2) and one Se(2) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Na(3), one Na(5), and one Se(1) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Na(3), one Na(4), and one Se(2) atom. In the fifth O site, O(5) is bonded in a distorted water-like geometry to one Na(2), one Na(3), one H(1), and one H(3) atom. In the sixth O site, O(6) is bonded in a distorted water-like geometry to one Na(1), one Na(3), one H(2), and one H(4) atom. In the seventh O site, O(7) is bonded in a distorted rectangular see-saw-like geometry to one Na(2), one Na(3), one Na(5), and one Se(1) atom. In the eighth O site, O(8) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), one Na(3), one Na(4), and one Se(2) atom. In the ninth O site, O(9) is bonded in a 4-coordinate geometry to one Na(1), one Na(4), one Na(5), and one Se(3) atom. In the tenth O site, O(10) is bonded in a 4-coordinate geometry to one Na(2), one Na(4), one Na(5), and one Se(4) atom. In the eleventh O site, O(11) is bonded in a 4-coordinate geometry to one Na(1), one Na(5), one H(7), and one Se(3) atom. In the twelfth O site, O(12) is bonded in a 4-coordinate geometry to one Na(2), one Na(4), one H(7), and one Se(4) atom. In the thirteenth O site, O(13) is bonded in a 3-coordinate geometry to one Na(2), one H(5), and one Se(1) atom. In the fourteenth O site, O(14) is bonded in a 3-coordinate geometry to one Na(1), one H(6), and one Se(2) atom. In the fifteenth O site, O(15) is bonded in a distorted trigonal planar geometry to one Na(4), one H(5), and one Se(3) atom. In the sixteenth O site, O(16) is bonded in a distorted trigonal planar geometry to one Na(5), one H(6), and one Se(4) atom. In the seventeenth O site, O(17) is bonded in a water-like geometry to one Na(1) and one Se(3) atom. In the eighteenth O site, O(18) is bonded in a distorted water-like geometry to one Na(2) and one Se(4) atom.