Li6CuF8 crystallizes in the monoclinic C2/m space group. There are four inequivalent Li sites. In the first Li site, Li(1) is bonded in a rectangular see-saw-like geometry to one F(2), one F(3), and two equivalent F(1) atoms. In the second Li site, Li(2) is bonded to two equivalent F(2) and four equivalent F(1) atoms to form LiF6 octahedra that share edges with two equivalent Li(3)F6 octahedra, edges with two equivalent Cu(1)F6 octahedra, and edges with four equivalent Li(4)F6 octahedra. In the third Li site, Li(3) is bonded to two equivalent F(3) and four equivalent F(1) atoms to form LiF6 octahedra that share corners with six equivalent Cu(1)F6 octahedra, edges with two equivalent Li(2)F6 octahedra, and edges with four equivalent Li(4)F6 octahedra. The corner-sharing octahedral tilt angles range from 0-3°. In the fourth Li site, Li(4) is bonded to two equivalent F(1), two equivalent F(2), and two equivalent F(3) atoms to form LiF6 octahedra that share edges with two equivalent Li(2)F6 octahedra, edges with two equivalent Li(3)F6 octahedra, edges with two equivalent Li(4)F6 octahedra, and edges with two equivalent Cu(1)F6 octahedra. Cu(1) is bonded to two equivalent F(3) and four equivalent F(1) atoms to form CuF6 octahedra that share corners with six equivalent Li(3)F6 octahedra, edges with two equivalent Li(2)F6 octahedra, and edges with four equivalent Li(4)F6 octahedra. The corner-sharing octahedral tilt angles range from 0-3°. There are three inequivalent F sites. In the first F site, F(1) is bonded to one Li(1), one Li(2), one Li(3), one Li(4), and one Cu(1) atom to form FLi4Cu square pyramids that share corners with five equivalent F(1)Li4Cu square pyramids, corners with three equivalent F(2)Li4 tetrahedra,  a cornercorner with one F(3)Li4Cu trigonal bipyramid, edges with three equivalent F(1)Li4Cu square pyramids,  an edgeedge with one F(2)Li4 tetrahedra, and edges with three equivalent F(3)Li4Cu trigonal bipyramids. In the second F site, F(2) is bonded to one Li(1), one Li(2), and two equivalent Li(4) atoms to form FLi4 tetrahedra that share corners with six equivalent F(1)Li4Cu square pyramids, corners with three equivalent F(2)Li4 tetrahedra, corners with three equivalent F(3)Li4Cu trigonal bipyramids, edges with two equivalent F(1)Li4Cu square pyramids, and  an edgeedge with one F(3)Li4Cu trigonal bipyramid. In the third F site, F(3) is bonded to one Li(1), one Li(3), two equivalent Li(4), and one Cu(1) atom to form distorted FLi4Cu trigonal bipyramids that share corners with two equivalent F(1)Li4Cu square pyramids, corners with three equivalent F(2)Li4 tetrahedra, corners with four equivalent F(3)Li4Cu trigonal bipyramids, edges with six equivalent F(1)Li4Cu square pyramids, and  an edgeedge with one F(2)Li4 tetrahedra.
Li6CuF8 crystallizes in the monoclinic C2/m space group. There are four inequivalent Li sites. In the first Li site, Li(1) is bonded in a rectangular see-saw-like geometry to one F(2), one F(3), and two equivalent F(1) atoms. The Li(1)-F(2) bond length is 1.80 Å. The Li(1)-F(3) bond length is 1.91 Å. Both Li(1)-F(1) bond lengths are 2.02 Å. In the second Li site, Li(2) is bonded to two equivalent F(2) and four equivalent F(1) atoms to form LiF6 octahedra that share edges with two equivalent Li(3)F6 octahedra, edges with two equivalent Cu(1)F6 octahedra, and edges with four equivalent Li(4)F6 octahedra. Both Li(2)-F(2) bond lengths are 1.91 Å. All Li(2)-F(1) bond lengths are 2.13 Å. In the third Li site, Li(3) is bonded to two equivalent F(3) and four equivalent F(1) atoms to form LiF6 octahedra that share corners with six equivalent Cu(1)F6 octahedra, edges with two equivalent Li(2)F6 octahedra, and edges with four equivalent Li(4)F6 octahedra. The corner-sharing octahedral tilt angles range from 0-3°. Both Li(3)-F(3) bond lengths are 1.95 Å. All Li(3)-F(1) bond lengths are 2.17 Å. In the fourth Li site, Li(4) is bonded to two equivalent F(1), two equivalent F(2), and two equivalent F(3) atoms to form LiF6 octahedra that share edges with two equivalent Li(2)F6 octahedra, edges with two equivalent Li(3)F6 octahedra, edges with two equivalent Li(4)F6 octahedra, and edges with two equivalent Cu(1)F6 octahedra. Both Li(4)-F(1) bond lengths are 2.19 Å. Both Li(4)-F(2) bond lengths are 1.90 Å. Both Li(4)-F(3) bond lengths are 2.07 Å. Cu(1) is bonded to two equivalent F(3) and four equivalent F(1) atoms to form CuF6 octahedra that share corners with six equivalent Li(3)F6 octahedra, edges with two equivalent Li(2)F6 octahedra, and edges with four equivalent Li(4)F6 octahedra. The corner-sharing octahedral tilt angles range from 0-3°. Both Cu(1)-F(3) bond lengths are 2.38 Å. All Cu(1)-F(1) bond lengths are 1.97 Å. There are three inequivalent F sites. In the first F site, F(1) is bonded to one Li(1), one Li(2), one Li(3), one Li(4), and one Cu(1) atom to form FLi4Cu square pyramids that share corners with five equivalent F(1)Li4Cu square pyramids, corners with three equivalent F(2)Li4 tetrahedra,  a cornercorner with one F(3)Li4Cu trigonal bipyramid, edges with three equivalent F(1)Li4Cu square pyramids,  an edgeedge with one F(2)Li4 tetrahedra, and edges with three equivalent F(3)Li4Cu trigonal bipyramids. In the second F site, F(2) is bonded to one Li(1), one Li(2), and two equivalent Li(4) atoms to form FLi4 tetrahedra that share corners with six equivalent F(1)Li4Cu square pyramids, corners with three equivalent F(2)Li4 tetrahedra, corners with three equivalent F(3)Li4Cu trigonal bipyramids, edges with two equivalent F(1)Li4Cu square pyramids, and  an edgeedge with one F(3)Li4Cu trigonal bipyramid. In the third F site, F(3) is bonded to one Li(1), one Li(3), two equivalent Li(4), and one Cu(1) atom to form distorted FLi4Cu trigonal bipyramids that share corners with two equivalent F(1)Li4Cu square pyramids, corners with three equivalent F(2)Li4 tetrahedra, corners with four equivalent F(3)Li4Cu trigonal bipyramids, edges with six equivalent F(1)Li4Cu square pyramids, and  an edgeedge with one F(2)Li4 tetrahedra.