KEuF4 crystallizes in the orthorhombic Pnma space group. K(1) is bonded in a 7-coordinate geometry to one F(3), two equivalent F(1), and four equivalent F(4) atoms. Eu(1) is bonded in a 9-coordinate geometry to one F(4), two equivalent F(1), three equivalent F(2), and three equivalent F(3) atoms. There are four inequivalent F sites. In the first F site, F(1) is bonded to two equivalent K(1) and two equivalent Eu(1) atoms to form FK2Eu2 tetrahedra that share corners with four equivalent F(1)K2Eu2 tetrahedra, corners with six equivalent F(3)KEu3 tetrahedra, and  an edgeedge with one F(3)KEu3 tetrahedra. In the second F site, F(2) is bonded in a distorted trigonal non-coplanar geometry to three equivalent Eu(1) atoms. In the third F site, F(3) is bonded to one K(1) and three equivalent Eu(1) atoms to form FKEu3 tetrahedra that share corners with two equivalent F(3)KEu3 tetrahedra, corners with six equivalent F(1)K2Eu2 tetrahedra,  an edgeedge with one F(1)K2Eu2 tetrahedra, and edges with two equivalent F(3)KEu3 tetrahedra. In the fourth F site, F(4) is bonded in a 5-coordinate geometry to four equivalent K(1) and one Eu(1) atom.
KEuF4 crystallizes in the orthorhombic Pnma space group. K(1) is bonded in a 7-coordinate geometry to one F(3), two equivalent F(1), and four equivalent F(4) atoms. The K(1)-F(3) bond length is 2.58 Å. There is one shorter (2.58 Å) and one longer (2.65 Å) K(1)-F(1) bond length. There are two shorter (2.68 Å) and two longer (2.70 Å) K(1)-F(4) bond lengths. Eu(1) is bonded in a 9-coordinate geometry to one F(4), two equivalent F(1), three equivalent F(2), and three equivalent F(3) atoms. The Eu(1)-F(4) bond length is 2.26 Å. Both Eu(1)-F(1) bond lengths are 2.32 Å. There is one shorter (2.38 Å) and two longer (2.49 Å) Eu(1)-F(2) bond lengths. There is one shorter (2.39 Å) and two longer (2.41 Å) Eu(1)-F(3) bond lengths. There are four inequivalent F sites. In the first F site, F(1) is bonded to two equivalent K(1) and two equivalent Eu(1) atoms to form FK2Eu2 tetrahedra that share corners with four equivalent F(1)K2Eu2 tetrahedra, corners with six equivalent F(3)KEu3 tetrahedra, and  an edgeedge with one F(3)KEu3 tetrahedra. In the second F site, F(2) is bonded in a distorted trigonal non-coplanar geometry to three equivalent Eu(1) atoms. In the third F site, F(3) is bonded to one K(1) and three equivalent Eu(1) atoms to form FKEu3 tetrahedra that share corners with two equivalent F(3)KEu3 tetrahedra, corners with six equivalent F(1)K2Eu2 tetrahedra,  an edgeedge with one F(1)K2Eu2 tetrahedra, and edges with two equivalent F(3)KEu3 tetrahedra. In the fourth F site, F(4) is bonded in a 5-coordinate geometry to four equivalent K(1) and one Eu(1) atom.