NpO5I crystallizes in the orthorhombic Pna2_1 space group. Np(1) is bonded to one O(3), one O(4), one O(5), two equivalent O(1), and two equivalent O(2) atoms to form distorted corner-sharing NpO7 pentagonal bipyramids. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted linear geometry to two equivalent Np(1) atoms. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to two equivalent Np(1) atoms. In the third O site, O(3) is bonded in a bent 120 degrees geometry to one Np(1) and one I(1) atom. In the fourth O site, O(4) is bonded in a bent 120 degrees geometry to one Np(1) and one I(1) atom. In the fifth O site, O(5) is bonded in a distorted bent 150 degrees geometry to one Np(1) and one I(1) atom. I(1) is bonded in a 3-coordinate geometry to one O(3), one O(4), and one O(5) atom.
NpO5I crystallizes in the orthorhombic Pna2_1 space group. Np(1) is bonded to one O(3), one O(4), one O(5), two equivalent O(1), and two equivalent O(2) atoms to form distorted corner-sharing NpO7 pentagonal bipyramids. The Np(1)-O(3) bond length is 2.41 Å. The Np(1)-O(4) bond length is 2.40 Å. The Np(1)-O(5) bond length is 2.54 Å. There is one shorter (1.85 Å) and one longer (2.33 Å) Np(1)-O(1) bond length. There is one shorter (1.90 Å) and one longer (2.46 Å) Np(1)-O(2) bond length. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted linear geometry to two equivalent Np(1) atoms. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to two equivalent Np(1) atoms. In the third O site, O(3) is bonded in a bent 120 degrees geometry to one Np(1) and one I(1) atom. The O(3)-I(1) bond length is 1.80 Å. In the fourth O site, O(4) is bonded in a bent 120 degrees geometry to one Np(1) and one I(1) atom. The O(4)-I(1) bond length is 1.81 Å. In the fifth O site, O(5) is bonded in a distorted bent 150 degrees geometry to one Np(1) and one I(1) atom. The O(5)-I(1) bond length is 1.81 Å. I(1) is bonded in a 3-coordinate geometry to one O(3), one O(4), and one O(5) atom.