ErHfF7 crystallizes in the monoclinic P2_1 space group. Er(1) is bonded in a 8-coordinate geometry to one F(2), one F(3), one F(4), one F(5), one F(6), one F(7), and two equivalent F(1) atoms. Hf(1) is bonded in an octahedral geometry to one F(2), one F(3), one F(4), one F(5), one F(6), and one F(7) atom. There are seven inequivalent F sites. In the first F site, F(1) is bonded in a bent 150 degrees geometry to two equivalent Er(1) atoms. In the second F site, F(2) is bonded in a linear geometry to one Er(1) and one Hf(1) atom. In the third F site, F(3) is bonded in a linear geometry to one Er(1) and one Hf(1) atom. In the fourth F site, F(4) is bonded in a bent 150 degrees geometry to one Er(1) and one Hf(1) atom. In the fifth F site, F(5) is bonded in a linear geometry to one Er(1) and one Hf(1) atom. In the sixth F site, F(6) is bonded in a distorted bent 150 degrees geometry to one Er(1) and one Hf(1) atom. In the seventh F site, F(7) is bonded in a bent 150 degrees geometry to one Er(1) and one Hf(1) atom.
ErHfF7 crystallizes in the monoclinic P2_1 space group. Er(1) is bonded in a 8-coordinate geometry to one F(2), one F(3), one F(4), one F(5), one F(6), one F(7), and two equivalent F(1) atoms. The Er(1)-F(2) bond length is 2.20 Å. The Er(1)-F(3) bond length is 2.24 Å. The Er(1)-F(4) bond length is 2.29 Å. The Er(1)-F(5) bond length is 2.29 Å. The Er(1)-F(6) bond length is 2.32 Å. The Er(1)-F(7) bond length is 2.25 Å. There is one shorter (2.14 Å) and one longer (2.18 Å) Er(1)-F(1) bond length. Hf(1) is bonded in an octahedral geometry to one F(2), one F(3), one F(4), one F(5), one F(6), and one F(7) atom. The Hf(1)-F(2) bond length is 1.99 Å. The Hf(1)-F(3) bond length is 2.00 Å. The Hf(1)-F(4) bond length is 1.99 Å. The Hf(1)-F(5) bond length is 1.98 Å. The Hf(1)-F(6) bond length is 1.99 Å. The Hf(1)-F(7) bond length is 2.00 Å. There are seven inequivalent F sites. In the first F site, F(1) is bonded in a bent 150 degrees geometry to two equivalent Er(1) atoms. In the second F site, F(2) is bonded in a linear geometry to one Er(1) and one Hf(1) atom. In the third F site, F(3) is bonded in a linear geometry to one Er(1) and one Hf(1) atom. In the fourth F site, F(4) is bonded in a bent 150 degrees geometry to one Er(1) and one Hf(1) atom. In the fifth F site, F(5) is bonded in a linear geometry to one Er(1) and one Hf(1) atom. In the sixth F site, F(6) is bonded in a distorted bent 150 degrees geometry to one Er(1) and one Hf(1) atom. In the seventh F site, F(7) is bonded in a bent 150 degrees geometry to one Er(1) and one Hf(1) atom.