Ir2Sn3Se3 is Spinel-like structured and crystallizes in the trigonal R-3 space group. There are two inequivalent Ir sites. In the first Ir site, Ir(1) is bonded to three equivalent Sn(1) and three equivalent Se(1) atoms to form IrSn3Se3 octahedra that share corners with six equivalent Ir(2)Sn3Se3 octahedra, corners with six equivalent Sn(2)Ir2Se2 tetrahedra, and corners with six equivalent Se(2)Sn2Ir2 tetrahedra. The corner-sharing octahedral tilt angles range from 54-60°. In the second Ir site, Ir(2) is bonded to one Sn(1), two equivalent Sn(2), one Se(1), and two equivalent Se(2) atoms to form IrSn3Se3 octahedra that share corners with two equivalent Ir(1)Sn3Se3 octahedra, corners with four equivalent Ir(2)Sn3Se3 octahedra, corners with two equivalent Sn(2)Ir2Se2 tetrahedra, corners with two equivalent Se(2)Sn2Ir2 tetrahedra, corners with four equivalent Sn(1)Ir2Se2 tetrahedra, and corners with four equivalent Se(1)Sn2Ir2 tetrahedra. The corner-sharing octahedral tilt angles range from 54-60°. There are two inequivalent Sn sites. In the first Sn site, Sn(1) is bonded to one Ir(1), one Ir(2), and two equivalent Se(2) atoms to form distorted SnIr2Se2 tetrahedra that share corners with four equivalent Ir(2)Sn3Se3 octahedra, corners with two equivalent Sn(1)Ir2Se2 tetrahedra, corners with two equivalent Sn(2)Ir2Se2 tetrahedra, corners with two equivalent Se(2)Sn2Ir2 tetrahedra, corners with four equivalent Se(1)Sn2Ir2 tetrahedra, and  an edgeedge with one Sn(1)Ir2Se2 tetrahedra. The corner-sharing octahedral tilt angles range from 69-71°. In the second Sn site, Sn(2) is bonded to two equivalent Ir(2) and two equivalent Se(1) atoms to form distorted SnIr2Se2 tetrahedra that share corners with two equivalent Ir(1)Sn3Se3 octahedra, corners with two equivalent Ir(2)Sn3Se3 octahedra, corners with two equivalent Sn(1)Ir2Se2 tetrahedra, corners with two equivalent Sn(2)Ir2Se2 tetrahedra, corners with two equivalent Se(1)Sn2Ir2 tetrahedra, corners with four equivalent Se(2)Sn2Ir2 tetrahedra, and  an edgeedge with one Sn(2)Ir2Se2 tetrahedra. The corner-sharing octahedral tilt angles range from 69-71°. There are two inequivalent Se sites. In the first Se site, Se(2) is bonded to two equivalent Ir(2) and two equivalent Sn(1) atoms to form SeSn2Ir2 tetrahedra that share corners with two equivalent Ir(1)Sn3Se3 octahedra, corners with two equivalent Ir(2)Sn3Se3 octahedra, corners with two equivalent Sn(1)Ir2Se2 tetrahedra, corners with two equivalent Se(1)Sn2Ir2 tetrahedra, corners with two equivalent Se(2)Sn2Ir2 tetrahedra, corners with four equivalent Sn(2)Ir2Se2 tetrahedra, and  an edgeedge with one Se(2)Sn2Ir2 tetrahedra. The corner-sharing octahedral tilt angles range from 68-74°. In the second Se site, Se(1) is bonded to one Ir(1), one Ir(2), and two equivalent Sn(2) atoms to form SeSn2Ir2 tetrahedra that share corners with four equivalent Ir(2)Sn3Se3 octahedra, corners with two equivalent Sn(2)Ir2Se2 tetrahedra, corners with two equivalent Se(1)Sn2Ir2 tetrahedra, corners with two equivalent Se(2)Sn2Ir2 tetrahedra, corners with four equivalent Sn(1)Ir2Se2 tetrahedra, and  an edgeedge with one Se(1)Sn2Ir2 tetrahedra. The corner-sharing octahedral tilt angles range from 67-74°.
Ir2Sn3Se3 is Spinel-like structured and crystallizes in the trigonal R-3 space group. There are two inequivalent Ir sites. In the first Ir site, Ir(1) is bonded to three equivalent Sn(1) and three equivalent Se(1) atoms to form IrSn3Se3 octahedra that share corners with six equivalent Ir(2)Sn3Se3 octahedra, corners with six equivalent Sn(2)Ir2Se2 tetrahedra, and corners with six equivalent Se(2)Sn2Ir2 tetrahedra. The corner-sharing octahedral tilt angles range from 54-60°. All Ir(1)-Sn(1) bond lengths are 2.58 Å. All Ir(1)-Se(1) bond lengths are 2.55 Å. In the second Ir site, Ir(2) is bonded to one Sn(1), two equivalent Sn(2), one Se(1), and two equivalent Se(2) atoms to form IrSn3Se3 octahedra that share corners with two equivalent Ir(1)Sn3Se3 octahedra, corners with four equivalent Ir(2)Sn3Se3 octahedra, corners with two equivalent Sn(2)Ir2Se2 tetrahedra, corners with two equivalent Se(2)Sn2Ir2 tetrahedra, corners with four equivalent Sn(1)Ir2Se2 tetrahedra, and corners with four equivalent Se(1)Sn2Ir2 tetrahedra. The corner-sharing octahedral tilt angles range from 54-60°. The Ir(2)-Sn(1) bond length is 2.58 Å. There is one shorter (2.56 Å) and one longer (2.59 Å) Ir(2)-Sn(2) bond length. The Ir(2)-Se(1) bond length is 2.56 Å. There is one shorter (2.53 Å) and one longer (2.58 Å) Ir(2)-Se(2) bond length. There are two inequivalent Sn sites. In the first Sn site, Sn(1) is bonded to one Ir(1), one Ir(2), and two equivalent Se(2) atoms to form distorted SnIr2Se2 tetrahedra that share corners with four equivalent Ir(2)Sn3Se3 octahedra, corners with two equivalent Sn(1)Ir2Se2 tetrahedra, corners with two equivalent Sn(2)Ir2Se2 tetrahedra, corners with two equivalent Se(2)Sn2Ir2 tetrahedra, corners with four equivalent Se(1)Sn2Ir2 tetrahedra, and  an edgeedge with one Sn(1)Ir2Se2 tetrahedra. The corner-sharing octahedral tilt angles range from 69-71°. There is one shorter (2.71 Å) and one longer (2.89 Å) Sn(1)-Se(2) bond length. In the second Sn site, Sn(2) is bonded to two equivalent Ir(2) and two equivalent Se(1) atoms to form distorted SnIr2Se2 tetrahedra that share corners with two equivalent Ir(1)Sn3Se3 octahedra, corners with two equivalent Ir(2)Sn3Se3 octahedra, corners with two equivalent Sn(1)Ir2Se2 tetrahedra, corners with two equivalent Sn(2)Ir2Se2 tetrahedra, corners with two equivalent Se(1)Sn2Ir2 tetrahedra, corners with four equivalent Se(2)Sn2Ir2 tetrahedra, and  an edgeedge with one Sn(2)Ir2Se2 tetrahedra. The corner-sharing octahedral tilt angles range from 69-71°. There is one shorter (2.70 Å) and one longer (2.89 Å) Sn(2)-Se(1) bond length. There are two inequivalent Se sites. In the first Se site, Se(2) is bonded to two equivalent Ir(2) and two equivalent Sn(1) atoms to form SeSn2Ir2 tetrahedra that share corners with two equivalent Ir(1)Sn3Se3 octahedra, corners with two equivalent Ir(2)Sn3Se3 octahedra, corners with two equivalent Sn(1)Ir2Se2 tetrahedra, corners with two equivalent Se(1)Sn2Ir2 tetrahedra, corners with two equivalent Se(2)Sn2Ir2 tetrahedra, corners with four equivalent Sn(2)Ir2Se2 tetrahedra, and  an edgeedge with one Se(2)Sn2Ir2 tetrahedra. The corner-sharing octahedral tilt angles range from 68-74°. In the second Se site, Se(1) is bonded to one Ir(1), one Ir(2), and two equivalent Sn(2) atoms to form SeSn2Ir2 tetrahedra that share corners with four equivalent Ir(2)Sn3Se3 octahedra, corners with two equivalent Sn(2)Ir2Se2 tetrahedra, corners with two equivalent Se(1)Sn2Ir2 tetrahedra, corners with two equivalent Se(2)Sn2Ir2 tetrahedra, corners with four equivalent Sn(1)Ir2Se2 tetrahedra, and  an edgeedge with one Se(1)Sn2Ir2 tetrahedra. The corner-sharing octahedral tilt angles range from 67-74°.