Sr4SeS3 is Caswellsilverite-like structured and crystallizes in the monoclinic C2/m space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to one Se(1), two equivalent S(2), and three equivalent S(1) atoms to form SrSeS5 octahedra that share corners with three equivalent Sr(2)Se2S4 octahedra, corners with three equivalent Sr(1)SeS5 octahedra, edges with five equivalent Sr(1)SeS5 octahedra, and edges with seven equivalent Sr(2)Se2S4 octahedra. The corner-sharing octahedral tilt angles range from 0-2°. In the second Sr site, Sr(2) is bonded to two equivalent Se(1), one S(2), and three equivalent S(1) atoms to form SrSe2S4 octahedra that share corners with three equivalent Sr(2)Se2S4 octahedra, corners with three equivalent Sr(1)SeS5 octahedra, edges with five equivalent Sr(2)Se2S4 octahedra, and edges with seven equivalent Sr(1)SeS5 octahedra. The corner-sharing octahedral tilt angles range from 0-2°. Se(1) is bonded to two equivalent Sr(1) and four equivalent Sr(2) atoms to form SeSr6 octahedra that share corners with six equivalent S(1)Sr6 octahedra, edges with two equivalent Se(1)Sr6 octahedra, edges with four equivalent S(2)Sr6 octahedra, and edges with six equivalent S(1)Sr6 octahedra. The corner-sharing octahedral tilt angles are 1°. There are two inequivalent S sites. In the first S site, S(1) is bonded to three equivalent Sr(1) and three equivalent Sr(2) atoms to form SSr6 octahedra that share corners with three equivalent Se(1)Sr6 octahedra, corners with three equivalent S(2)Sr6 octahedra, edges with three equivalent Se(1)Sr6 octahedra, edges with three equivalent S(2)Sr6 octahedra, and edges with six equivalent S(1)Sr6 octahedra. The corner-sharing octahedral tilt angles range from 1-3°. In the second S site, S(2) is bonded to two equivalent Sr(2) and four equivalent Sr(1) atoms to form SSr6 octahedra that share corners with six equivalent S(1)Sr6 octahedra, edges with two equivalent S(2)Sr6 octahedra, edges with four equivalent Se(1)Sr6 octahedra, and edges with six equivalent S(1)Sr6 octahedra. The corner-sharing octahedral tilt angles range from 1-3°.
Sr4SeS3 is Caswellsilverite-like structured and crystallizes in the monoclinic C2/m space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to one Se(1), two equivalent S(2), and three equivalent S(1) atoms to form SrSeS5 octahedra that share corners with three equivalent Sr(2)Se2S4 octahedra, corners with three equivalent Sr(1)SeS5 octahedra, edges with five equivalent Sr(1)SeS5 octahedra, and edges with seven equivalent Sr(2)Se2S4 octahedra. The corner-sharing octahedral tilt angles range from 0-2°. The Sr(1)-Se(1) bond length is 3.09 Å. Both Sr(1)-S(2) bond lengths are 3.04 Å. There is one shorter (3.02 Å) and two longer (3.05 Å) Sr(1)-S(1) bond lengths. In the second Sr site, Sr(2) is bonded to two equivalent Se(1), one S(2), and three equivalent S(1) atoms to form SrSe2S4 octahedra that share corners with three equivalent Sr(2)Se2S4 octahedra, corners with three equivalent Sr(1)SeS5 octahedra, edges with five equivalent Sr(2)Se2S4 octahedra, and edges with seven equivalent Sr(1)SeS5 octahedra. The corner-sharing octahedral tilt angles range from 0-2°. Both Sr(2)-Se(1) bond lengths are 3.10 Å. The Sr(2)-S(2) bond length is 3.05 Å. There are two shorter (3.02 Å) and one longer (3.06 Å) Sr(2)-S(1) bond length. Se(1) is bonded to two equivalent Sr(1) and four equivalent Sr(2) atoms to form SeSr6 octahedra that share corners with six equivalent S(1)Sr6 octahedra, edges with two equivalent Se(1)Sr6 octahedra, edges with four equivalent S(2)Sr6 octahedra, and edges with six equivalent S(1)Sr6 octahedra. The corner-sharing octahedral tilt angles are 1°. There are two inequivalent S sites. In the first S site, S(1) is bonded to three equivalent Sr(1) and three equivalent Sr(2) atoms to form SSr6 octahedra that share corners with three equivalent Se(1)Sr6 octahedra, corners with three equivalent S(2)Sr6 octahedra, edges with three equivalent Se(1)Sr6 octahedra, edges with three equivalent S(2)Sr6 octahedra, and edges with six equivalent S(1)Sr6 octahedra. The corner-sharing octahedral tilt angles range from 1-3°. In the second S site, S(2) is bonded to two equivalent Sr(2) and four equivalent Sr(1) atoms to form SSr6 octahedra that share corners with six equivalent S(1)Sr6 octahedra, edges with two equivalent S(2)Sr6 octahedra, edges with four equivalent Se(1)Sr6 octahedra, and edges with six equivalent S(1)Sr6 octahedra. The corner-sharing octahedral tilt angles range from 1-3°.