HfTa2VC4 is alpha Po-derived structured and crystallizes in the trigonal R3m space group. Hf(1) is bonded to three equivalent C(1) and three equivalent C(3) atoms to form HfC6 octahedra that share corners with three equivalent Ta(2)C6 octahedra, corners with three equivalent V(1)C6 octahedra, edges with three equivalent Ta(2)C6 octahedra, edges with three equivalent V(1)C6 octahedra, and edges with six equivalent Hf(1)C6 octahedra. The corner-sharing octahedral tilt angles range from 2-4°. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to three equivalent C(2) and three equivalent C(4) atoms to form TaC6 octahedra that share corners with three equivalent Ta(2)C6 octahedra, corners with three equivalent V(1)C6 octahedra, edges with three equivalent Ta(2)C6 octahedra, edges with three equivalent V(1)C6 octahedra, and edges with six equivalent Ta(1)C6 octahedra. The corner-sharing octahedral tilt angles range from 0-2°. In the second Ta site, Ta(2) is bonded to three equivalent C(1) and three equivalent C(2) atoms to form TaC6 octahedra that share corners with three equivalent Hf(1)C6 octahedra, corners with three equivalent Ta(1)C6 octahedra, edges with three equivalent Hf(1)C6 octahedra, edges with three equivalent Ta(1)C6 octahedra, and edges with six equivalent Ta(2)C6 octahedra. The corner-sharing octahedral tilt angles range from 0-2°. V(1) is bonded to three equivalent C(3) and three equivalent C(4) atoms to form VC6 octahedra that share corners with three equivalent Hf(1)C6 octahedra, corners with three equivalent Ta(1)C6 octahedra, edges with three equivalent Hf(1)C6 octahedra, edges with three equivalent Ta(1)C6 octahedra, and edges with six equivalent V(1)C6 octahedra. The corner-sharing octahedral tilt angles range from 2-4°. There are four inequivalent C sites. In the first C site, C(1) is bonded to three equivalent Hf(1) and three equivalent Ta(2) atoms to form CHf3Ta3 octahedra that share corners with three equivalent C(3)Hf3V3 octahedra, corners with three equivalent C(2)Ta6 octahedra, edges with three equivalent C(3)Hf3V3 octahedra, edges with three equivalent C(2)Ta6 octahedra, and edges with six equivalent C(1)Hf3Ta3 octahedra. The corner-sharing octahedral tilt angles range from 0-1°. In the second C site, C(2) is bonded to three equivalent Ta(1) and three equivalent Ta(2) atoms to form CTa6 octahedra that share corners with three equivalent C(1)Hf3Ta3 octahedra, corners with three equivalent C(4)Ta3V3 octahedra, edges with three equivalent C(1)Hf3Ta3 octahedra, edges with three equivalent C(4)Ta3V3 octahedra, and edges with six equivalent C(2)Ta6 octahedra. The corner-sharing octahedral tilt angles range from 0-1°. In the third C site, C(3) is bonded to three equivalent Hf(1) and three equivalent V(1) atoms to form CHf3V3 octahedra that share corners with three equivalent C(1)Hf3Ta3 octahedra, corners with three equivalent C(4)Ta3V3 octahedra, edges with three equivalent C(1)Hf3Ta3 octahedra, edges with three equivalent C(4)Ta3V3 octahedra, and edges with six equivalent C(3)Hf3V3 octahedra. The corner-sharing octahedral tilt angles range from 0-1°. In the fourth C site, C(4) is bonded to three equivalent Ta(1) and three equivalent V(1) atoms to form CTa3V3 octahedra that share corners with three equivalent C(3)Hf3V3 octahedra, corners with three equivalent C(2)Ta6 octahedra, edges with three equivalent C(3)Hf3V3 octahedra, edges with three equivalent C(2)Ta6 octahedra, and edges with six equivalent C(4)Ta3V3 octahedra. The corner-sharing octahedral tilt angles range from 0-1°.
HfTa2VC4 is alpha Po-derived structured and crystallizes in the trigonal R3m space group. Hf(1) is bonded to three equivalent C(1) and three equivalent C(3) atoms to form HfC6 octahedra that share corners with three equivalent Ta(2)C6 octahedra, corners with three equivalent V(1)C6 octahedra, edges with three equivalent Ta(2)C6 octahedra, edges with three equivalent V(1)C6 octahedra, and edges with six equivalent Hf(1)C6 octahedra. The corner-sharing octahedral tilt angles range from 2-4°. All Hf(1)-C(1) bond lengths are 2.30 Å. All Hf(1)-C(3) bond lengths are 2.26 Å. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to three equivalent C(2) and three equivalent C(4) atoms to form TaC6 octahedra that share corners with three equivalent Ta(2)C6 octahedra, corners with three equivalent V(1)C6 octahedra, edges with three equivalent Ta(2)C6 octahedra, edges with three equivalent V(1)C6 octahedra, and edges with six equivalent Ta(1)C6 octahedra. The corner-sharing octahedral tilt angles range from 0-2°. All Ta(1)-C(2) bond lengths are 2.25 Å. All Ta(1)-C(4) bond lengths are 2.21 Å. In the second Ta site, Ta(2) is bonded to three equivalent C(1) and three equivalent C(2) atoms to form TaC6 octahedra that share corners with three equivalent Hf(1)C6 octahedra, corners with three equivalent Ta(1)C6 octahedra, edges with three equivalent Hf(1)C6 octahedra, edges with three equivalent Ta(1)C6 octahedra, and edges with six equivalent Ta(2)C6 octahedra. The corner-sharing octahedral tilt angles range from 0-2°. All Ta(2)-C(1) bond lengths are 2.23 Å. All Ta(2)-C(2) bond lengths are 2.23 Å. V(1) is bonded to three equivalent C(3) and three equivalent C(4) atoms to form VC6 octahedra that share corners with three equivalent Hf(1)C6 octahedra, corners with three equivalent Ta(1)C6 octahedra, edges with three equivalent Hf(1)C6 octahedra, edges with three equivalent Ta(1)C6 octahedra, and edges with six equivalent V(1)C6 octahedra. The corner-sharing octahedral tilt angles range from 2-4°. All V(1)-C(3) bond lengths are 2.16 Å. All V(1)-C(4) bond lengths are 2.15 Å. There are four inequivalent C sites. In the first C site, C(1) is bonded to three equivalent Hf(1) and three equivalent Ta(2) atoms to form CHf3Ta3 octahedra that share corners with three equivalent C(3)Hf3V3 octahedra, corners with three equivalent C(2)Ta6 octahedra, edges with three equivalent C(3)Hf3V3 octahedra, edges with three equivalent C(2)Ta6 octahedra, and edges with six equivalent C(1)Hf3Ta3 octahedra. The corner-sharing octahedral tilt angles range from 0-1°. In the second C site, C(2) is bonded to three equivalent Ta(1) and three equivalent Ta(2) atoms to form CTa6 octahedra that share corners with three equivalent C(1)Hf3Ta3 octahedra, corners with three equivalent C(4)Ta3V3 octahedra, edges with three equivalent C(1)Hf3Ta3 octahedra, edges with three equivalent C(4)Ta3V3 octahedra, and edges with six equivalent C(2)Ta6 octahedra. The corner-sharing octahedral tilt angles range from 0-1°. In the third C site, C(3) is bonded to three equivalent Hf(1) and three equivalent V(1) atoms to form CHf3V3 octahedra that share corners with three equivalent C(1)Hf3Ta3 octahedra, corners with three equivalent C(4)Ta3V3 octahedra, edges with three equivalent C(1)Hf3Ta3 octahedra, edges with three equivalent C(4)Ta3V3 octahedra, and edges with six equivalent C(3)Hf3V3 octahedra. The corner-sharing octahedral tilt angles range from 0-1°. In the fourth C site, C(4) is bonded to three equivalent Ta(1) and three equivalent V(1) atoms to form CTa3V3 octahedra that share corners with three equivalent C(3)Hf3V3 octahedra, corners with three equivalent C(2)Ta6 octahedra, edges with three equivalent C(3)Hf3V3 octahedra, edges with three equivalent C(2)Ta6 octahedra, and edges with six equivalent C(4)Ta3V3 octahedra. The corner-sharing octahedral tilt angles range from 0-1°.