Np(CrAl2)4 crystallizes in the tetragonal I4/mmm space group. Np(1) is bonded in a 20-coordinate geometry to eight equivalent Cr(1), four equivalent Al(1), and eight equivalent Al(2) atoms. Cr(1) is bonded to two equivalent Np(1), two equivalent Cr(1), four equivalent Al(1), and four equivalent Al(2) atoms to form a mixture of distorted face, corner, and edge-sharing CrNp2Al8Cr2 cuboctahedra. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded in a 10-coordinate geometry to one Np(1), four equivalent Cr(1), one Al(1), and four equivalent Al(2) atoms. In the second Al site, Al(2) is bonded in a 12-coordinate geometry to two equivalent Np(1), four equivalent Cr(1), two equivalent Al(2), and four equivalent Al(1) atoms.
Np(CrAl2)4 crystallizes in the tetragonal I4/mmm space group. Np(1) is bonded in a 20-coordinate geometry to eight equivalent Cr(1), four equivalent Al(1), and eight equivalent Al(2) atoms. All Np(1)-Cr(1) bond lengths are 3.35 Å. All Np(1)-Al(1) bond lengths are 2.99 Å. All Np(1)-Al(2) bond lengths are 3.13 Å. Cr(1) is bonded to two equivalent Np(1), two equivalent Cr(1), four equivalent Al(1), and four equivalent Al(2) atoms to form a mixture of distorted face, corner, and edge-sharing CrNp2Al8Cr2 cuboctahedra. Both Cr(1)-Cr(1) bond lengths are 2.48 Å. All Cr(1)-Al(1) bond lengths are 2.64 Å. All Cr(1)-Al(2) bond lengths are 2.54 Å. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded in a 10-coordinate geometry to one Np(1), four equivalent Cr(1), one Al(1), and four equivalent Al(2) atoms. The Al(1)-Al(1) bond length is 2.81 Å. There are two shorter (2.71 Å) and two longer (2.86 Å) Al(1)-Al(2) bond lengths. In the second Al site, Al(2) is bonded in a 12-coordinate geometry to two equivalent Np(1), four equivalent Cr(1), two equivalent Al(2), and four equivalent Al(1) atoms. Both Al(2)-Al(2) bond lengths are 2.70 Å.