NpFeGa5 crystallizes in the tetragonal P4/mmm space group. Np(1) is bonded to four equivalent Ga(2) and eight Ga(1,1) atoms to form distorted NpGa12 cuboctahedra that share corners with four equivalent Np(1)Ga12 cuboctahedra, faces with four equivalent Np(1)Ga12 cuboctahedra, and faces with four equivalent Ga(2)Np4Ga8 cuboctahedra. Fe(1) is bonded in a distorted body-centered cubic geometry to eight Ga(1,1) atoms. There are three inequivalent Ga sites. In the first Ga site, Ga(1) is bonded in a 11-coordinate geometry to two equivalent Np(1); two equivalent Fe(1); two equivalent Ga(2); and five Ga(1,1) atoms. In the second Ga site, Ga(1) is bonded in a 11-coordinate geometry to two equivalent Np(1); two equivalent Fe(1); two equivalent Ga(2); and five Ga(1,1) atoms. In the third Ga site, Ga(2) is bonded to four equivalent Np(1) and eight Ga(1,1) atoms to form GaNp4Ga8 cuboctahedra that share corners with four equivalent Ga(2)Np4Ga8 cuboctahedra, faces with four equivalent Np(1)Ga12 cuboctahedra, and faces with four equivalent Ga(2)Np4Ga8 cuboctahedra.
NpFeGa5 crystallizes in the tetragonal P4/mmm space group. Np(1) is bonded to four equivalent Ga(2) and eight Ga(1,1) atoms to form distorted NpGa12 cuboctahedra that share corners with four equivalent Np(1)Ga12 cuboctahedra, faces with four equivalent Np(1)Ga12 cuboctahedra, and faces with four equivalent Ga(2)Np4Ga8 cuboctahedra. All Np(1)-Ga(2) bond lengths are 3.06 Å. All Np(1)-Ga(1,1) bond lengths are 2.98 Å. Fe(1) is bonded in a distorted body-centered cubic geometry to eight Ga(1,1) atoms. All Fe(1)-Ga(1,1) bond lengths are 2.52 Å. There are three inequivalent Ga sites. In the first Ga site, Ga(1) is bonded in a 11-coordinate geometry to two equivalent Np(1); two equivalent Fe(1); two equivalent Ga(2); and five Ga(1,1) atoms. Both Ga(1)-Ga(2) bond lengths are 2.98 Å. There is one shorter (2.56 Å) and four longer (3.06 Å) Ga(1)-Ga(1,1) bond lengths. In the second Ga site, Ga(1) is bonded in a 11-coordinate geometry to two equivalent Np(1); two equivalent Fe(1); two equivalent Ga(2); and five Ga(1,1) atoms. Both Ga(1)-Ga(2) bond lengths are 2.98 Å. All Ga(1)-Ga(1) bond lengths are 3.06 Å. In the third Ga site, Ga(2) is bonded to four equivalent Np(1) and eight Ga(1,1) atoms to form GaNp4Ga8 cuboctahedra that share corners with four equivalent Ga(2)Np4Ga8 cuboctahedra, faces with four equivalent Np(1)Ga12 cuboctahedra, and faces with four equivalent Ga(2)Np4Ga8 cuboctahedra.