Ta3Co3C crystallizes in the cubic Fd-3m space group. Ta(1) is bonded in a 2-coordinate geometry to two equivalent Co(1), four equivalent Co(2), and two equivalent C(1) atoms. There are two inequivalent Co sites. In the first Co site, Co(2) is bonded in a distorted q6 geometry to six equivalent Ta(1), three equivalent Co(1), and three equivalent Co(2) atoms. In the second Co site, Co(1) is bonded to six equivalent Ta(1) and six equivalent Co(2) atoms to form CoTa6Co6 cuboctahedra that share edges with six equivalent C(1)Ta6 octahedra and faces with six equivalent Co(1)Ta6Co6 cuboctahedra. C(1) is bonded to six equivalent Ta(1) atoms to form CTa6 octahedra that share corners with six equivalent C(1)Ta6 octahedra and edges with six equivalent Co(1)Ta6Co6 cuboctahedra. The corner-sharing octahedral tilt angles are 45°.
Ta3Co3C crystallizes in the cubic Fd-3m space group. Ta(1) is bonded in a 2-coordinate geometry to two equivalent Co(1), four equivalent Co(2), and two equivalent C(1) atoms. Both Ta(1)-Co(1) bond lengths are 2.83 Å. There are two shorter (2.75 Å) and two longer (2.82 Å) Ta(1)-Co(2) bond lengths. Both Ta(1)-C(1) bond lengths are 2.16 Å. There are two inequivalent Co sites. In the first Co site, Co(2) is bonded in a distorted q6 geometry to six equivalent Ta(1), three equivalent Co(1), and three equivalent Co(2) atoms. All Co(2)-Co(1) bond lengths are 2.42 Å. All Co(2)-Co(2) bond lengths are 2.52 Å. In the second Co site, Co(1) is bonded to six equivalent Ta(1) and six equivalent Co(2) atoms to form CoTa6Co6 cuboctahedra that share edges with six equivalent C(1)Ta6 octahedra and faces with six equivalent Co(1)Ta6Co6 cuboctahedra. C(1) is bonded to six equivalent Ta(1) atoms to form CTa6 octahedra that share corners with six equivalent C(1)Ta6 octahedra and edges with six equivalent Co(1)Ta6Co6 cuboctahedra. The corner-sharing octahedral tilt angles are 45°.