HfCo3B2 crystallizes in the trigonal R-3m space group. There are two inequivalent Hf sites. In the first Hf site, Hf(1) is bonded to two equivalent Hf(2), six equivalent Co(1), and six equivalent Co(2) atoms to form distorted corner-sharing HfHf2Co12 cuboctahedra. In the second Hf site, Hf(2) is bonded in a 20-coordinate geometry to one Hf(1), one Hf(2), three equivalent Co(1), nine equivalent Co(2), and six equivalent B(1) atoms. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded in a 4-coordinate geometry to two equivalent Hf(1), two equivalent Hf(2), and four equivalent B(1) atoms. In the second Co site, Co(2) is bonded in a 4-coordinate geometry to one Hf(1), three equivalent Hf(2), and four equivalent B(1) atoms. B(1) is bonded in a 9-coordinate geometry to two equivalent Hf(2), two equivalent Co(1), four equivalent Co(2), and one B(1) atom.
HfCo3B2 crystallizes in the trigonal R-3m space group. There are two inequivalent Hf sites. In the first Hf site, Hf(1) is bonded to two equivalent Hf(2), six equivalent Co(1), and six equivalent Co(2) atoms to form distorted corner-sharing HfHf2Co12 cuboctahedra. Both Hf(1)-Hf(2) bond lengths are 2.96 Å. All Hf(1)-Co(1) bond lengths are 2.82 Å. All Hf(1)-Co(2) bond lengths are 2.71 Å. In the second Hf site, Hf(2) is bonded in a 20-coordinate geometry to one Hf(1), one Hf(2), three equivalent Co(1), nine equivalent Co(2), and six equivalent B(1) atoms. The Hf(2)-Hf(2) bond length is 3.07 Å. All Hf(2)-Co(1) bond lengths are 2.80 Å. There are a spread of Hf(2)-Co(2) bond distances ranging from 2.71-2.98 Å. All Hf(2)-B(1) bond lengths are 2.61 Å. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded in a 4-coordinate geometry to two equivalent Hf(1), two equivalent Hf(2), and four equivalent B(1) atoms. All Co(1)-B(1) bond lengths are 2.18 Å. In the second Co site, Co(2) is bonded in a 4-coordinate geometry to one Hf(1), three equivalent Hf(2), and four equivalent B(1) atoms. There are two shorter (2.02 Å) and two longer (2.03 Å) Co(2)-B(1) bond lengths. B(1) is bonded in a 9-coordinate geometry to two equivalent Hf(2), two equivalent Co(1), four equivalent Co(2), and one B(1) atom. The B(1)-B(1) bond length is 2.06 Å.