NpNiGa5 crystallizes in the orthorhombic Pmmm space group. Np(1) is bonded to four equivalent Ga(1), four equivalent Ga(2), and four equivalent Ga(3) atoms to form 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(3)Np4Ga8 cuboctahedra. Ni(1) is bonded in a body-centered cubic geometry to four equivalent Ga(1) and four equivalent Ga(2) 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 Ni(1), one Ga(1), two equivalent Ga(3), and four equivalent Ga(2) atoms. In the second Ga site, Ga(2) is bonded in a 11-coordinate geometry to two equivalent Np(1), two equivalent Ni(1), one Ga(2), two equivalent Ga(3), and four equivalent Ga(1) atoms. In the third Ga site, Ga(3) is bonded to four equivalent Np(1), four equivalent Ga(1), and four equivalent Ga(2) atoms to form distorted GaNp4Ga8 cuboctahedra that share corners with four equivalent Ga(3)Np4Ga8 cuboctahedra, faces with four equivalent Np(1)Ga12 cuboctahedra, and faces with four equivalent Ga(3)Np4Ga8 cuboctahedra.
NpNiGa5 crystallizes in the orthorhombic Pmmm space group. Np(1) is bonded to four equivalent Ga(1), four equivalent Ga(2), and four equivalent Ga(3) atoms to form 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(3)Np4Ga8 cuboctahedra. All Np(1)-Ga(1) bond lengths are 2.96 Å. All Np(1)-Ga(2) bond lengths are 2.98 Å. All Np(1)-Ga(3) bond lengths are 2.99 Å. Ni(1) is bonded in a body-centered cubic geometry to four equivalent Ga(1) and four equivalent Ga(2) atoms. All Ni(1)-Ga(1) bond lengths are 2.47 Å. All Ni(1)-Ga(2) bond lengths are 2.49 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 Ni(1), one Ga(1), two equivalent Ga(3), and four equivalent Ga(2) atoms. The Ga(1)-Ga(1) bond length is 2.60 Å. Both Ga(1)-Ga(3) bond lengths are 2.98 Å. All Ga(1)-Ga(2) bond lengths are 2.99 Å. In the second Ga site, Ga(2) is bonded in a 11-coordinate geometry to two equivalent Np(1), two equivalent Ni(1), one Ga(2), two equivalent Ga(3), and four equivalent Ga(1) atoms. The Ga(2)-Ga(2) bond length is 2.60 Å. Both Ga(2)-Ga(3) bond lengths are 2.96 Å. In the third Ga site, Ga(3) is bonded to four equivalent Np(1), four equivalent Ga(1), and four equivalent Ga(2) atoms to form distorted GaNp4Ga8 cuboctahedra that share corners with four equivalent Ga(3)Np4Ga8 cuboctahedra, faces with four equivalent Np(1)Ga12 cuboctahedra, and faces with four equivalent Ga(3)Np4Ga8 cuboctahedra.