HfFeGe2 crystallizes in the orthorhombic Pbam space group. There are two inequivalent Hf sites. In the first Hf site, Hf(1) is bonded in a 8-coordinate geometry to one Ge(4), one Ge(5), two equivalent Ge(1), two equivalent Ge(2), and two equivalent Ge(3) atoms. In the second Hf site, Hf(2) is bonded in a 7-coordinate geometry to two equivalent Ge(1), two equivalent Ge(2), and three equivalent Ge(4) atoms. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 6-coordinate geometry to one Ge(2), one Ge(3), one Ge(4), one Ge(5), and two equivalent Ge(1) atoms. In the second Fe site, Fe(2) is bonded to two equivalent Ge(1), two equivalent Ge(4), and two equivalent Ge(5) atoms to form distorted edge-sharing FeGe6 cuboctahedra. There are five inequivalent Ge sites. In the first Ge site, Ge(2) is bonded in a 9-coordinate geometry to two equivalent Hf(2), four equivalent Hf(1), two equivalent Fe(1), and one Ge(2) atom. In the second Ge site, Ge(3) is bonded in a 7-coordinate geometry to four equivalent Hf(1), two equivalent Fe(1), and one Ge(3) atom. In the third Ge site, Ge(4) is bonded in a 9-coordinate geometry to two equivalent Hf(1), three equivalent Hf(2), two equivalent Fe(1), and two equivalent Fe(2) atoms. In the fourth Ge site, Ge(5) is bonded in a 6-coordinate geometry to two equivalent Hf(1), two equivalent Fe(1), and two equivalent Fe(2) atoms. In the fifth Ge site, Ge(1) is bonded in a 7-coordinate geometry to one Hf(2), two equivalent Hf(1), one Fe(2), two equivalent Fe(1), and one Ge(1) atom.
HfFeGe2 crystallizes in the orthorhombic Pbam space group. There are two inequivalent Hf sites. In the first Hf site, Hf(1) is bonded in a 8-coordinate geometry to one Ge(4), one Ge(5), two equivalent Ge(1), two equivalent Ge(2), and two equivalent Ge(3) atoms. The Hf(1)-Ge(4) bond length is 2.70 Å. The Hf(1)-Ge(5) bond length is 2.78 Å. There is one shorter (2.86 Å) and one longer (2.90 Å) Hf(1)-Ge(1) bond length. There is one shorter (2.84 Å) and one longer (2.86 Å) Hf(1)-Ge(2) bond length. There is one shorter (2.90 Å) and one longer (2.96 Å) Hf(1)-Ge(3) bond length. In the second Hf site, Hf(2) is bonded in a 7-coordinate geometry to two equivalent Ge(1), two equivalent Ge(2), and three equivalent Ge(4) atoms. Both Hf(2)-Ge(1) bond lengths are 2.72 Å. There is one shorter (2.75 Å) and one longer (2.77 Å) Hf(2)-Ge(2) bond length. There are a spread of Hf(2)-Ge(4) bond distances ranging from 2.78-2.92 Å. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 6-coordinate geometry to one Ge(2), one Ge(3), one Ge(4), one Ge(5), and two equivalent Ge(1) atoms. The Fe(1)-Ge(2) bond length is 2.40 Å. The Fe(1)-Ge(3) bond length is 2.39 Å. The Fe(1)-Ge(4) bond length is 2.52 Å. The Fe(1)-Ge(5) bond length is 2.55 Å. There is one shorter (2.48 Å) and one longer (2.51 Å) Fe(1)-Ge(1) bond length. In the second Fe site, Fe(2) is bonded to two equivalent Ge(1), two equivalent Ge(4), and two equivalent Ge(5) atoms to form distorted edge-sharing FeGe6 cuboctahedra. Both Fe(2)-Ge(1) bond lengths are 2.46 Å. Both Fe(2)-Ge(4) bond lengths are 2.49 Å. Both Fe(2)-Ge(5) bond lengths are 2.52 Å. There are five inequivalent Ge sites. In the first Ge site, Ge(2) is bonded in a 9-coordinate geometry to two equivalent Hf(2), four equivalent Hf(1), two equivalent Fe(1), and one Ge(2) atom. The Ge(2)-Ge(2) bond length is 2.55 Å. In the second Ge site, Ge(3) is bonded in a 7-coordinate geometry to four equivalent Hf(1), two equivalent Fe(1), and one Ge(3) atom. The Ge(3)-Ge(3) bond length is 2.61 Å. In the third Ge site, Ge(4) is bonded in a 9-coordinate geometry to two equivalent Hf(1), three equivalent Hf(2), two equivalent Fe(1), and two equivalent Fe(2) atoms. In the fourth Ge site, Ge(5) is bonded in a 6-coordinate geometry to two equivalent Hf(1), two equivalent Fe(1), and two equivalent Fe(2) atoms. In the fifth Ge site, Ge(1) is bonded in a 7-coordinate geometry to one Hf(2), two equivalent Hf(1), one Fe(2), two equivalent Fe(1), and one Ge(1) atom. The Ge(1)-Ge(1) bond length is 2.48 Å.