Nb4Ni2C crystallizes in the cubic Fd-3m space group. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded in a distorted bent 150 degrees geometry to four equivalent Ni(1) and two equivalent C(1) atoms. In the second Nb site, Nb(2) is bonded in a distorted hexagonal planar geometry to six equivalent Ni(1) atoms. Ni(1) is bonded to three equivalent Nb(2), six equivalent Nb(1), and three equivalent Ni(1) atoms to form distorted NiNb9Ni3 cuboctahedra that share corners with six equivalent Ni(1)Nb9Ni3 cuboctahedra, corners with three equivalent C(1)Nb6 octahedra, faces with nine equivalent Ni(1)Nb9Ni3 cuboctahedra, and faces with three equivalent C(1)Nb6 octahedra. The corner-sharing octahedral tilt angles are 47°. C(1) is bonded to six equivalent Nb(1) atoms to form CNb6 octahedra that share corners with six equivalent Ni(1)Nb9Ni3 cuboctahedra, corners with six equivalent C(1)Nb6 octahedra, and faces with six equivalent Ni(1)Nb9Ni3 cuboctahedra. The corner-sharing octahedral tilt angles are 37°.
Nb4Ni2C crystallizes in the cubic Fd-3m space group. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded in a distorted bent 150 degrees geometry to four equivalent Ni(1) and two equivalent C(1) atoms. There are two shorter (2.84 Å) and two longer (3.07 Å) Nb(1)-Ni(1) bond lengths. Both Nb(1)-C(1) bond lengths are 2.18 Å. In the second Nb site, Nb(2) is bonded in a distorted hexagonal planar geometry to six equivalent Ni(1) atoms. All Nb(2)-Ni(1) bond lengths are 2.51 Å. Ni(1) is bonded to three equivalent Nb(2), six equivalent Nb(1), and three equivalent Ni(1) atoms to form distorted NiNb9Ni3 cuboctahedra that share corners with six equivalent Ni(1)Nb9Ni3 cuboctahedra, corners with three equivalent C(1)Nb6 octahedra, faces with nine equivalent Ni(1)Nb9Ni3 cuboctahedra, and faces with three equivalent C(1)Nb6 octahedra. The corner-sharing octahedral tilt angles are 47°. All Ni(1)-Ni(1) bond lengths are 2.61 Å. C(1) is bonded to six equivalent Nb(1) atoms to form CNb6 octahedra that share corners with six equivalent Ni(1)Nb9Ni3 cuboctahedra, corners with six equivalent C(1)Nb6 octahedra, and faces with six equivalent Ni(1)Nb9Ni3 cuboctahedra. The corner-sharing octahedral tilt angles are 37°.