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 43-49°. In the second Na site, Na(2) is bonded in a 4-coordinate geometry to one O(1), one O(2), one O(3), and one O(5) atom. 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 43-49°. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 150 degrees geometry to one Na(2) and one Np(1) atom. In the second O site, O(2) is bonded in a distorted trigonal non-coplanar geometry to one Na(1), one Na(2), and one Np(1) atom. In the third O site, O(3) is bonded in a distorted 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 single-bond geometry to one O(5) atom. In the fifth O site, O(5) is bonded in a T-shaped geometry to one Na(1), one Na(2), 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 43-49°. Both Na(1)-O(2) bond lengths are 2.38 Å. Both Na(1)-O(3) bond lengths are 2.47 Å. Both Na(1)-O(5) bond lengths are 2.56 Å. In the second Na site, Na(2) is bonded in a 4-coordinate geometry to one O(1), one O(2), one O(3), and one O(5) atom. The Na(2)-O(1) bond length is 2.29 Å. The Na(2)-O(2) bond length is 2.34 Å. The Na(2)-O(3) bond length is 2.37 Å. The Na(2)-O(5) bond length is 2.64 Å. 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 43-49°. Both Np(1)-O(1) bond lengths are 1.95 Å. Both Np(1)-O(2) bond lengths are 1.96 Å. Both Np(1)-O(3) bond lengths are 1.95 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 150 degrees geometry to one Na(2) and one Np(1) atom. In the second O site, O(2) is bonded in a distorted trigonal non-coplanar geometry to one Na(1), one Na(2), and one Np(1) atom. In the third O site, O(3) is bonded in a distorted 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 single-bond geometry to one O(5) atom. The O(4)-O(5) bond length is 1.25 Å. In the fifth O site, O(5) is bonded in a T-shaped geometry to one Na(1), one Na(2), and one O(4) atom.