DOE OSTI2020
K2EuCl5 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. K1+ is bonded in a 8-coordinate geometry to eight Cl1- atoms. There are a spread of K–Cl bond distances ranging from 3.24–3.44 Å. Eu3+ is bonded to seven Cl1- atoms to form distorted edge-sharing EuCl7 pentagonal bipyramids. There are a spread of Eu–Cl bond distances ranging from 2.80–2.90 Å. There are four inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded to four equivalent K1+ and one Eu3+ atom to form distorted ClK4Eu trigonal bipyramids that share corners with four equivalent ClK2Eu2 tetrahedra, corners with eight ClK4Eu trigonal bipyramids, edges with four equivalent ClK2Eu2 tetrahedra, an edgeedge with one ClK4Eu trigonal bipyramid, and a faceface with one ClK4Eu trigonal bipyramid. In the second Cl1- site, Cl1- is bonded in a 5-coordinate geometry to four equivalent K1+ and one Eu3+ atom. In the third Cl1- site, Cl1- is bonded to four equivalent K1+ and one Eu3+ atom to form distorted ClK4Eu trigonal bipyramids that share corners with eight equivalent ClK2Eu2 tetrahedra, corners with four equivalent ClK4Eu trigonal bipyramids, edges with two equivalent ClK2Eu2 tetrahedra, edges with three ClK4Eu trigonal bipyramids, and a faceface with one ClK4Eu trigonal bipyramid. In the fourth Cl1- site, Cl1- is bonded to two equivalent K1+ and two equivalent Eu3+ atoms to form distorted ClK2Eu2 tetrahedra that share corners with six equivalent ClK2Eu2 tetrahedra, corners with six ClK4Eu trigonal bipyramids, an edgeedge with one ClK2Eu2 tetrahedra, and edges with three ClK4Eu trigonal bipyramids.