NpAl4 crystallizes in the orthorhombic Imma space group. Np(1) is bonded in a 13-coordinate geometry to three equivalent Al(2), four equivalent Al(1), and six equivalent Al(3) atoms. There are three inequivalent Al sites. In the first Al site, Al(3) is bonded in a 10-coordinate geometry to three equivalent Np(1), one Al(1), three equivalent Al(2), and three equivalent Al(3) atoms. In the second Al site, Al(1) is bonded to four equivalent Np(1), two equivalent Al(3), and four equivalent Al(2) atoms to form a mixture of distorted edge and face-sharing AlNp4Al6 cuboctahedra. In the third Al site, Al(2) is bonded in a 13-coordinate geometry to three equivalent Np(1), four equivalent Al(1), and six equivalent Al(3) atoms.
NpAl4 crystallizes in the orthorhombic Imma space group. Np(1) is bonded in a 13-coordinate geometry to three equivalent Al(2), four equivalent Al(1), and six equivalent Al(3) atoms. There is one shorter (3.10 Å) and two longer (3.12 Å) Np(1)-Al(2) bond lengths. All Np(1)-Al(1) bond lengths are 3.11 Å. There are four shorter (3.07 Å) and two longer (3.15 Å) Np(1)-Al(3) bond lengths. There are three inequivalent Al sites. In the first Al site, Al(3) is bonded in a 10-coordinate geometry to three equivalent Np(1), one Al(1), three equivalent Al(2), and three equivalent Al(3) atoms. The Al(3)-Al(1) bond length is 2.73 Å. There are two shorter (2.84 Å) and one longer (2.91 Å) Al(3)-Al(2) bond length. There are two shorter (2.62 Å) and one longer (2.72 Å) Al(3)-Al(3) bond length. In the second Al site, Al(1) is bonded to four equivalent Np(1), two equivalent Al(3), and four equivalent Al(2) atoms to form a mixture of distorted edge and face-sharing AlNp4Al6 cuboctahedra. All Al(1)-Al(2) bond lengths are 3.12 Å. In the third Al site, Al(2) is bonded in a 13-coordinate geometry to three equivalent Np(1), four equivalent Al(1), and six equivalent Al(3) atoms.