Cs4Sr(SnSe3)3 crystallizes in the trigonal R3 space group. There are two inequivalent Cs sites. In the first Cs site, Cs(1) is bonded in a 8-coordinate geometry to two equivalent Se(1), three equivalent Se(2), and three equivalent Se(3) atoms. In the second Cs site, Cs(2) is bonded in a 9-coordinate geometry to three equivalent Se(1), three equivalent Se(2), and three equivalent Se(3) atoms. Sr(1) is bonded to three equivalent Se(2) and three equivalent Se(3) atoms to form SrSe6 octahedra that share corners with six equivalent Sn(1)Se4 tetrahedra. Sn(1) is bonded to one Se(2), one Se(3), and two equivalent Se(1) atoms to form SnSe4 tetrahedra that share corners with two equivalent Sr(1)Se6 octahedra and corners with two equivalent Sn(1)Se4 tetrahedra. The corner-sharing octahedral tilt angles range from 66-68°. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded in a distorted water-like geometry to one Cs(2), two equivalent Cs(1), and two equivalent Sn(1) atoms. In the second Se site, Se(2) is bonded in a 6-coordinate geometry to one Cs(2), three equivalent Cs(1), one Sr(1), and one Sn(1) atom. In the third Se site, Se(3) is bonded in a 6-coordinate geometry to one Cs(2), three equivalent Cs(1), one Sr(1), and one Sn(1) atom.
Cs4Sr(SnSe3)3 crystallizes in the trigonal R3 space group. There are two inequivalent Cs sites. In the first Cs site, Cs(1) is bonded in a 8-coordinate geometry to two equivalent Se(1), three equivalent Se(2), and three equivalent Se(3) atoms. There is one shorter (3.92 Å) and one longer (4.02 Å) Cs(1)-Se(1) bond length. There are two shorter (3.71 Å) and one longer (3.99 Å) Cs(1)-Se(2) bond length. There are a spread of Cs(1)-Se(3) bond distances ranging from 3.97-4.05 Å. In the second Cs site, Cs(2) is bonded in a 9-coordinate geometry to three equivalent Se(1), three equivalent Se(2), and three equivalent Se(3) atoms. All Cs(2)-Se(1) bond lengths are 4.20 Å. All Cs(2)-Se(2) bond lengths are 3.90 Å. All Cs(2)-Se(3) bond lengths are 3.93 Å. Sr(1) is bonded to three equivalent Se(2) and three equivalent Se(3) atoms to form SrSe6 octahedra that share corners with six equivalent Sn(1)Se4 tetrahedra. All Sr(1)-Se(2) bond lengths are 3.17 Å. All Sr(1)-Se(3) bond lengths are 3.17 Å. Sn(1) is bonded to one Se(2), one Se(3), and two equivalent Se(1) atoms to form SnSe4 tetrahedra that share corners with two equivalent Sr(1)Se6 octahedra and corners with two equivalent Sn(1)Se4 tetrahedra. The corner-sharing octahedral tilt angles range from 66-68°. The Sn(1)-Se(2) bond length is 2.53 Å. The Sn(1)-Se(3) bond length is 2.52 Å. There is one shorter (2.60 Å) and one longer (2.63 Å) Sn(1)-Se(1) bond length. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded in a distorted water-like geometry to one Cs(2), two equivalent Cs(1), and two equivalent Sn(1) atoms. In the second Se site, Se(2) is bonded in a 6-coordinate geometry to one Cs(2), three equivalent Cs(1), one Sr(1), and one Sn(1) atom. In the third Se site, Se(3) is bonded in a 6-coordinate geometry to one Cs(2), three equivalent Cs(1), one Sr(1), and one Sn(1) atom.