Ti2Ta2Ni2C crystallizes in the tetragonal I-4m2 space group. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded in a 6-coordinate geometry to three equivalent Ni(1) and three equivalent Ni(2) atoms. In the second Ti site, Ti(2) is bonded in a distorted bent 150 degrees geometry to two equivalent Ni(1), two equivalent Ni(2), and two equivalent C(1) atoms. There are three inequivalent Ta sites. In the first Ta site, Ta(1) is bonded in a distorted bent 150 degrees geometry to two equivalent Ni(1), two equivalent Ni(2), and two equivalent C(1) atoms. In the second Ta site, Ta(2) is bonded in a distorted bent 150 degrees geometry to two equivalent Ni(1) and two equivalent C(1) atoms. In the third Ta site, Ta(3) is bonded in a distorted bent 150 degrees geometry to two equivalent Ni(1) and two equivalent C(1) atoms. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded in a 12-coordinate geometry to two equivalent Ti(2), three equivalent Ti(1), one Ta(1), one Ta(3), two equivalent Ta(2), and three equivalent Ni(1) atoms. In the second Ni site, Ni(2) is bonded in a 6-coordinate geometry to two equivalent Ti(2), three equivalent Ti(1), and one Ta(1) atom. C(1) is bonded to two equivalent Ti(2), one Ta(1), one Ta(3), and two equivalent Ta(2) atoms to form corner-sharing CTa4Ti2 octahedra. The corner-sharing octahedral tilt angles range from 35-39°.
Ti2Ta2Ni2C crystallizes in the tetragonal I-4m2 space group. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded in a 6-coordinate geometry to three equivalent Ni(1) and three equivalent Ni(2) atoms. All Ti(1)-Ni(1) bond lengths are 2.49 Å. All Ti(1)-Ni(2) bond lengths are 2.51 Å. In the second Ti site, Ti(2) is bonded in a distorted bent 150 degrees geometry to two equivalent Ni(1), two equivalent Ni(2), and two equivalent C(1) atoms. Both Ti(2)-Ni(1) bond lengths are 3.03 Å. Both Ti(2)-Ni(2) bond lengths are 2.66 Å. Both Ti(2)-C(1) bond lengths are 2.12 Å. There are three inequivalent Ta sites. In the first Ta site, Ta(1) is bonded in a distorted bent 150 degrees geometry to two equivalent Ni(1), two equivalent Ni(2), and two equivalent C(1) atoms. Both Ta(1)-Ni(1) bond lengths are 3.00 Å. Both Ta(1)-Ni(2) bond lengths are 2.68 Å. Both Ta(1)-C(1) bond lengths are 2.16 Å. In the second Ta site, Ta(2) is bonded in a distorted bent 150 degrees geometry to two equivalent Ni(1) and two equivalent C(1) atoms. Both Ta(2)-Ni(1) bond lengths are 2.77 Å. Both Ta(2)-C(1) bond lengths are 2.17 Å. In the third Ta site, Ta(3) is bonded in a distorted bent 150 degrees geometry to two equivalent Ni(1) and two equivalent C(1) atoms. Both Ta(3)-Ni(1) bond lengths are 2.78 Å. Both Ta(3)-C(1) bond lengths are 2.15 Å. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded in a 12-coordinate geometry to two equivalent Ti(2), three equivalent Ti(1), one Ta(1), one Ta(3), two equivalent Ta(2), and three equivalent Ni(1) atoms. There are two shorter (2.61 Å) and one longer (2.62 Å) Ni(1)-Ni(1) bond length. In the second Ni site, Ni(2) is bonded in a 6-coordinate geometry to two equivalent Ti(2), three equivalent Ti(1), and one Ta(1) atom. C(1) is bonded to two equivalent Ti(2), one Ta(1), one Ta(3), and two equivalent Ta(2) atoms to form corner-sharing CTa4Ti2 octahedra. The corner-sharing octahedral tilt angles range from 35-39°.