Hf4Ni4Si7 crystallizes in the tetragonal I4/mmm space group. There are two inequivalent Hf sites. In the first Hf site, Hf(1) is bonded in a 7-coordinate geometry to four equivalent Ni(1), two equivalent Si(2), two equivalent Si(4), and three equivalent Si(3) atoms. In the second Hf site, Hf(2) is bonded in a 7-coordinate geometry to four equivalent Ni(1), one Si(1), two equivalent Si(2), two equivalent Si(3), and two equivalent Si(4) atoms. Ni(1) is bonded to two equivalent Hf(1), two equivalent Hf(2), two equivalent Ni(1), two equivalent Si(1), two equivalent Si(3), and two equivalent Si(4) atoms to form a mixture of distorted edge, face, and corner-sharing NiHf4Si6Ni2 cuboctahedra. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded in a 6-coordinate geometry to one Hf(2), four equivalent Ni(1), and one Si(1) atom. In the second Si site, Si(2) is bonded in a 10-coordinate geometry to four equivalent Hf(1), four equivalent Hf(2), and two equivalent Si(2) atoms. In the third Si site, Si(3) is bonded in a 9-coordinate geometry to two equivalent Hf(2), three equivalent Hf(1), and four equivalent Ni(1) atoms. In the fourth Si site, Si(4) is bonded in a 8-coordinate geometry to two equivalent Hf(1), two equivalent Hf(2), and four equivalent Ni(1) atoms.
Hf4Ni4Si7 crystallizes in the tetragonal I4/mmm space group. There are two inequivalent Hf sites. In the first Hf site, Hf(1) is bonded in a 7-coordinate geometry to four equivalent Ni(1), two equivalent Si(2), two equivalent Si(4), and three equivalent Si(3) atoms. All Hf(1)-Ni(1) bond lengths are 3.07 Å. Both Hf(1)-Si(2) bond lengths are 2.79 Å. Both Hf(1)-Si(4) bond lengths are 2.70 Å. There is one shorter (2.82 Å) and two longer (2.87 Å) Hf(1)-Si(3) bond lengths. In the second Hf site, Hf(2) is bonded in a 7-coordinate geometry to four equivalent Ni(1), one Si(1), two equivalent Si(2), two equivalent Si(3), and two equivalent Si(4) atoms. All Hf(2)-Ni(1) bond lengths are 3.05 Å. The Hf(2)-Si(1) bond length is 2.75 Å. Both Hf(2)-Si(2) bond lengths are 2.81 Å. Both Hf(2)-Si(3) bond lengths are 2.69 Å. Both Hf(2)-Si(4) bond lengths are 2.87 Å. Ni(1) is bonded to two equivalent Hf(1), two equivalent Hf(2), two equivalent Ni(1), two equivalent Si(1), two equivalent Si(3), and two equivalent Si(4) atoms to form a mixture of distorted edge, face, and corner-sharing NiHf4Si6Ni2 cuboctahedra. Both Ni(1)-Ni(1) bond lengths are 2.55 Å. Both Ni(1)-Si(1) bond lengths are 2.39 Å. Both Ni(1)-Si(3) bond lengths are 2.39 Å. Both Ni(1)-Si(4) bond lengths are 2.40 Å. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded in a 6-coordinate geometry to one Hf(2), four equivalent Ni(1), and one Si(1) atom. The Si(1)-Si(1) bond length is 2.35 Å. In the second Si site, Si(2) is bonded in a 10-coordinate geometry to four equivalent Hf(1), four equivalent Hf(2), and two equivalent Si(2) atoms. There is one shorter (2.55 Å) and one longer (2.56 Å) Si(2)-Si(2) bond length. In the third Si site, Si(3) is bonded in a 9-coordinate geometry to two equivalent Hf(2), three equivalent Hf(1), and four equivalent Ni(1) atoms. In the fourth Si site, Si(4) is bonded in a 8-coordinate geometry to two equivalent Hf(1), two equivalent Hf(2), and four equivalent Ni(1) atoms.