Na3NpO10 crystallizes in the triclinic P-1 space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms to form NaO6 octahedra that share corners with four equivalent Np(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 26-61°. In the second Na site, Na(2) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(3), one O(5), and two equivalent O(4) atoms. Np(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form NpO6 octahedra that share corners with four equivalent Na(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 26-61°. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Na(2), one Np(1), and one O(5) atom. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to one Na(1), one Na(2), and one Np(1) atom. In the third O site, O(3) is bonded in a trigonal non-coplanar geometry to one Na(1), one Na(2), and one Np(1) atom. In the fourth O site, O(4) is bonded in a distorted T-shaped geometry to two equivalent Na(2) and one O(5) atom. In the fifth O site, O(5) is bonded in a see-saw-like geometry to one Na(1), one Na(2), one O(1), and one O(4) atom.
Na3NpO10 crystallizes in the triclinic P-1 space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms to form NaO6 octahedra that share corners with four equivalent Np(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 26-61°. Both Na(1)-O(2) bond lengths are 2.28 Å. Both Na(1)-O(3) bond lengths are 2.41 Å. Both Na(1)-O(5) bond lengths are 2.67 Å. In the second Na site, Na(2) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(3), one O(5), and two equivalent O(4) atoms. The Na(2)-O(1) bond length is 2.32 Å. The Na(2)-O(2) bond length is 2.81 Å. The Na(2)-O(3) bond length is 2.33 Å. The Na(2)-O(5) bond length is 2.80 Å. There is one shorter (2.83 Å) and one longer (2.91 Å) Na(2)-O(4) bond length. Np(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form NpO6 octahedra that share corners with four equivalent Na(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 26-61°. Both Np(1)-O(1) bond lengths are 2.45 Å. Both Np(1)-O(2) bond lengths are 1.88 Å. Both Np(1)-O(3) bond lengths are 1.90 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Na(2), one Np(1), and one O(5) atom. The O(1)-O(5) bond length is 1.41 Å. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to one Na(1), one Na(2), and one Np(1) atom. In the third O site, O(3) is bonded in a trigonal non-coplanar geometry to one Na(1), one Na(2), and one Np(1) atom. In the fourth O site, O(4) is bonded in a distorted T-shaped geometry to two equivalent Na(2) and one O(5) atom. The O(4)-O(5) bond length is 1.34 Å. In the fifth O site, O(5) is bonded in a see-saw-like geometry to one Na(1), one Na(2), one O(1), and one O(4) atom.