Eu3F4S2 crystallizes in the tetragonal I4/mmm space group. There are two inequivalent Eu sites. In the first Eu site, Eu(1) is bonded in a body-centered cubic geometry to eight equivalent F(1) atoms. In the second Eu site, Eu(2) is bonded in a 9-coordinate geometry to five equivalent S(1) and four equivalent F(1) atoms. S(1) is bonded to five equivalent Eu(2) atoms to form distorted SEu5 trigonal bipyramids that share corners with twelve equivalent F(1)Eu4 tetrahedra, corners with four equivalent S(1)Eu5 trigonal bipyramids, edges with four equivalent F(1)Eu4 tetrahedra, and edges with eight equivalent S(1)Eu5 trigonal bipyramids. F(1) is bonded to two equivalent Eu(1) and two equivalent Eu(2) atoms to form FEu4 tetrahedra that share corners with ten equivalent F(1)Eu4 tetrahedra, corners with six equivalent S(1)Eu5 trigonal bipyramids, edges with five equivalent F(1)Eu4 tetrahedra, and edges with two equivalent S(1)Eu5 trigonal bipyramids.
Eu3F4S2 crystallizes in the tetragonal I4/mmm space group. There are two inequivalent Eu sites. In the first Eu site, Eu(1) is bonded in a body-centered cubic geometry to eight equivalent F(1) atoms. All Eu(1)-F(1) bond lengths are 2.42 Å. In the second Eu site, Eu(2) is bonded in a 9-coordinate geometry to five equivalent S(1) and four equivalent F(1) atoms. There is one shorter (2.84 Å) and four longer (2.92 Å) Eu(2)-S(1) bond lengths. All Eu(2)-F(1) bond lengths are 2.62 Å. S(1) is bonded to five equivalent Eu(2) atoms to form distorted SEu5 trigonal bipyramids that share corners with twelve equivalent F(1)Eu4 tetrahedra, corners with four equivalent S(1)Eu5 trigonal bipyramids, edges with four equivalent F(1)Eu4 tetrahedra, and edges with eight equivalent S(1)Eu5 trigonal bipyramids. F(1) is bonded to two equivalent Eu(1) and two equivalent Eu(2) atoms to form FEu4 tetrahedra that share corners with ten equivalent F(1)Eu4 tetrahedra, corners with six equivalent S(1)Eu5 trigonal bipyramids, edges with five equivalent F(1)Eu4 tetrahedra, and edges with two equivalent S(1)Eu5 trigonal bipyramids.