DOE OSTI2020
Eu7(ClF6)2 crystallizes in the hexagonal P-6 space group. The structure is three-dimensional. there are three inequivalent Eu2+ sites. In the first Eu2+ site, Eu2+ is bonded in a 9-coordinate geometry to nine F1- atoms. There are three shorter (2.42 Å) and six longer (2.74 Å) Eu–F bond lengths. In the second Eu2+ site, Eu2+ is bonded in a 9-coordinate geometry to two equivalent Cl1- and seven F1- atoms. Both Eu–Cl bond lengths are 3.13 Å. There are a spread of Eu–F bond distances ranging from 2.46–2.82 Å. In the third Eu2+ site, Eu2+ is bonded in a 9-coordinate geometry to two equivalent Cl1- and seven F1- atoms. Both Eu–Cl bond lengths are 3.17 Å. There are a spread of Eu–F bond distances ranging from 2.50–2.62 Å. There are two inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a 12-coordinate geometry to six equivalent Eu2+ and nine F1- atoms. There are six shorter (3.30 Å) and three longer (3.43 Å) Cl–F bond lengths. In the second Cl1- site, Cl1- is bonded in a 12-coordinate geometry to six equivalent Eu2+ and six equivalent F1- atoms. All Cl–F bond lengths are 3.24 Å. There are four inequivalent F1- sites. In the first F1- site, F1- is bonded to four Eu2+ and one Cl1- atom to form FEu4Cl tetrahedra that share corners with twelve FEu4Cl tetrahedra, edges with three FEu4Cl2 tetrahedra, and faces with two equivalent FEu4Cl2 tetrahedra. In the second F1- site, F1- is bonded to four Eu2+ and two equivalent Cl1- atoms to form distorted FEu4Cl2 tetrahedra that share corners with twelve FEu4Cl tetrahedra, edges with five FEu4Cl tetrahedra, and faces with two equivalent FEu4Cl2 tetrahedra. In the third F1- site, F1- is bonded to four Eu2+ and two equivalent Cl1- atoms to form a mixture of edge, face, and corner-sharing FEu4Cl2 tetrahedra. In the fourth F1- site, F1- is bonded in a 5-coordinate geometry to five Eu2+ atoms.