Na3NpH2Se2O11 crystallizes in the triclinic P-1 space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to one O(3), one O(4), one O(5), one O(9), and two equivalent O(1) atoms. In the second Na site, Na(2) is bonded to one O(3), one O(5), one O(6), one O(8), and two equivalent O(2) atoms to form distorted NaO6 octahedra that share  a cornercorner with one Na(3)O7 pentagonal bipyramid,  a cornercorner with one Np(1)O7 pentagonal bipyramid,  a cornercorner with one Se(2)O4 tetrahedra, corners with three equivalent Se(1)O4 tetrahedra,  an edgeedge with one Na(2)O6 octahedra,  an edgeedge with one Np(1)O7 pentagonal bipyramid, and edges with two equivalent Na(3)O7 pentagonal bipyramids. In the third Na site, Na(3) is bonded to one O(10), one O(11), one O(2), one O(3), one O(7), and two equivalent O(8) atoms to form distorted NaO7 pentagonal bipyramids that share  a cornercorner with one Na(2)O6 octahedra,  a cornercorner with one Se(2)O4 tetrahedra, edges with two equivalent Na(2)O6 octahedra,  an edgeedge with one Na(3)O7 pentagonal bipyramid, edges with two equivalent Np(1)O7 pentagonal bipyramids, and edges with two equivalent Se(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 59°. Np(1) is bonded to one O(1), one O(10), one O(11), one O(2), one O(4), one O(6), and one O(7) atom to form distorted NpO7 pentagonal bipyramids that share  a cornercorner with one Na(2)O6 octahedra, corners with two equivalent Se(1)O4 tetrahedra, corners with two equivalent Se(2)O4 tetrahedra,  an edgeedge with one Na(2)O6 octahedra, and edges with two equivalent Na(3)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 53°. There are two inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(7) atom. In the second H site, H(2) is bonded in a single-bond geometry to one O(7) atom. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded to one O(11), one O(3), one O(6), and one O(8) atom to form SeO4 tetrahedra that share corners with three equivalent Na(2)O6 octahedra, corners with two equivalent Np(1)O7 pentagonal bipyramids, and edges with two equivalent Na(3)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 45-56°. In the second Se site, Se(2) is bonded to one O(10), one O(4), one O(5), and one O(9) atom to form SeO4 tetrahedra that share  a cornercorner with one Na(2)O6 octahedra,  a cornercorner with one Na(3)O7 pentagonal bipyramid, and corners with two equivalent Np(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 60°. There are eleven inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to two equivalent Na(1) and one Np(1) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Na(3), two equivalent Na(2), and one Np(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one Na(3), and one Se(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Na(1), one Np(1), and one Se(2) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Na(1), one Na(2), and one Se(2) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Na(2), one Np(1), and one Se(1) atom. In the seventh O site, O(7) is bonded in a water-like geometry to one Na(3), one Np(1), one H(1), and one H(2) atom. In the eighth O site, O(8) is bonded to one Na(2), two equivalent Na(3), and one Se(1) atom to form distorted edge-sharing ONa3Se trigonal pyramids. In the ninth O site, O(9) is bonded in a distorted bent 150 degrees geometry to one Na(1) and one Se(2) atom. In the tenth O site, O(10) is bonded in a 3-coordinate geometry to one Na(3), one Np(1), and one Se(2) atom. In the eleventh O site, O(11) is bonded in a 3-coordinate geometry to one Na(3), one Np(1), and one Se(1) atom.
Na3NpH2Se2O11 crystallizes in the triclinic P-1 space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to one O(3), one O(4), one O(5), one O(9), and two equivalent O(1) atoms. The Na(1)-O(3) bond length is 2.51 Å. The Na(1)-O(4) bond length is 2.77 Å. The Na(1)-O(5) bond length is 2.40 Å. The Na(1)-O(9) bond length is 2.35 Å. There is one shorter (2.35 Å) and one longer (2.66 Å) Na(1)-O(1) bond length. In the second Na site, Na(2) is bonded to one O(3), one O(5), one O(6), one O(8), and two equivalent O(2) atoms to form distorted NaO6 octahedra that share  a cornercorner with one Na(3)O7 pentagonal bipyramid,  a cornercorner with one Np(1)O7 pentagonal bipyramid,  a cornercorner with one Se(2)O4 tetrahedra, corners with three equivalent Se(1)O4 tetrahedra,  an edgeedge with one Na(2)O6 octahedra,  an edgeedge with one Np(1)O7 pentagonal bipyramid, and edges with two equivalent Na(3)O7 pentagonal bipyramids. The Na(2)-O(3) bond length is 2.38 Å. The Na(2)-O(5) bond length is 2.44 Å. The Na(2)-O(6) bond length is 2.66 Å. The Na(2)-O(8) bond length is 2.38 Å. There is one shorter (2.41 Å) and one longer (2.58 Å) Na(2)-O(2) bond length. In the third Na site, Na(3) is bonded to one O(10), one O(11), one O(2), one O(3), one O(7), and two equivalent O(8) atoms to form distorted NaO7 pentagonal bipyramids that share  a cornercorner with one Na(2)O6 octahedra,  a cornercorner with one Se(2)O4 tetrahedra, edges with two equivalent Na(2)O6 octahedra,  an edgeedge with one Na(3)O7 pentagonal bipyramid, edges with two equivalent Np(1)O7 pentagonal bipyramids, and edges with two equivalent Se(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 59°. The Na(3)-O(10) bond length is 2.47 Å. The Na(3)-O(11) bond length is 2.66 Å. The Na(3)-O(2) bond length is 2.69 Å. The Na(3)-O(3) bond length is 2.70 Å. The Na(3)-O(7) bond length is 2.61 Å. There is one shorter (2.48 Å) and one longer (2.65 Å) Na(3)-O(8) bond length. Np(1) is bonded to one O(1), one O(10), one O(11), one O(2), one O(4), one O(6), and one O(7) atom to form distorted NpO7 pentagonal bipyramids that share  a cornercorner with one Na(2)O6 octahedra, corners with two equivalent Se(1)O4 tetrahedra, corners with two equivalent Se(2)O4 tetrahedra,  an edgeedge with one Na(2)O6 octahedra, and edges with two equivalent Na(3)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 53°. The Np(1)-O(1) bond length is 1.84 Å. The Np(1)-O(10) bond length is 2.54 Å. The Np(1)-O(11) bond length is 2.45 Å. The Np(1)-O(2) bond length is 1.85 Å. The Np(1)-O(4) bond length is 2.47 Å. The Np(1)-O(6) bond length is 2.46 Å. The Np(1)-O(7) bond length is 2.61 Å. There are two inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(7) atom. The H(1)-O(7) bond length is 0.99 Å. In the second H site, H(2) is bonded in a single-bond geometry to one O(7) atom. The H(2)-O(7) bond length is 0.98 Å. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded to one O(11), one O(3), one O(6), and one O(8) atom to form SeO4 tetrahedra that share corners with three equivalent Na(2)O6 octahedra, corners with two equivalent Np(1)O7 pentagonal bipyramids, and edges with two equivalent Na(3)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 45-56°. The Se(1)-O(11) bond length is 1.69 Å. The Se(1)-O(3) bond length is 1.67 Å. The Se(1)-O(6) bond length is 1.68 Å. The Se(1)-O(8) bond length is 1.67 Å. In the second Se site, Se(2) is bonded to one O(10), one O(4), one O(5), and one O(9) atom to form SeO4 tetrahedra that share  a cornercorner with one Na(2)O6 octahedra,  a cornercorner with one Na(3)O7 pentagonal bipyramid, and corners with two equivalent Np(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 60°. The Se(2)-O(10) bond length is 1.68 Å. The Se(2)-O(4) bond length is 1.69 Å. The Se(2)-O(5) bond length is 1.67 Å. The Se(2)-O(9) bond length is 1.66 Å. There are eleven inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to two equivalent Na(1) and one Np(1) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Na(3), two equivalent Na(2), and one Np(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one Na(3), and one Se(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Na(1), one Np(1), and one Se(2) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Na(1), one Na(2), and one Se(2) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Na(2), one Np(1), and one Se(1) atom. In the seventh O site, O(7) is bonded in a water-like geometry to one Na(3), one Np(1), one H(1), and one H(2) atom. In the eighth O site, O(8) is bonded to one Na(2), two equivalent Na(3), and one Se(1) atom to form distorted edge-sharing ONa3Se trigonal pyramids. In the ninth O site, O(9) is bonded in a distorted bent 150 degrees geometry to one Na(1) and one Se(2) atom. In the tenth O site, O(10) is bonded in a 3-coordinate geometry to one Na(3), one Np(1), and one Se(2) atom. In the eleventh O site, O(11) is bonded in a 3-coordinate geometry to one Na(3), one Np(1), and one Se(1) atom.