Ta4Co2C crystallizes in the cubic Fd-3m space group. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded in a 6-coordinate geometry to six equivalent Co(1) atoms. In the second Ta site, Ta(2) is bonded in a distorted bent 150 degrees geometry to four equivalent Co(1) and two equivalent C(1) atoms. Co(1) is bonded in a 12-coordinate geometry to three equivalent Ta(1), six equivalent Ta(2), and three equivalent Co(1) atoms. C(1) is bonded to six equivalent Ta(2) atoms to form corner-sharing CTa6 octahedra. The corner-sharing octahedral tilt angles are 39°.
Ta4Co2C crystallizes in the cubic Fd-3m space group. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded in a 6-coordinate geometry to six equivalent Co(1) atoms. All Ta(1)-Co(1) bond lengths are 2.51 Å. In the second Ta site, Ta(2) is bonded in a distorted bent 150 degrees geometry to four equivalent Co(1) and two equivalent C(1) atoms. There are two shorter (2.78 Å) and two longer (3.00 Å) Ta(2)-Co(1) bond lengths. Both Ta(2)-C(1) bond lengths are 2.18 Å. Co(1) is bonded in a 12-coordinate geometry to three equivalent Ta(1), six equivalent Ta(2), and three equivalent Co(1) atoms. All Co(1)-Co(1) bond lengths are 2.70 Å. C(1) is bonded to six equivalent Ta(2) atoms to form corner-sharing CTa6 octahedra. The corner-sharing octahedral tilt angles are 39°.