Rh3Se8 crystallizes in the trigonal R-3 space group. Rh(1) is bonded to two equivalent Se(2) and four equivalent Se(1) atoms to form RhSe6 octahedra that share corners with eight equivalent Rh(1)Se6 octahedra and corners with two equivalent Se(2)Rh3Se tetrahedra. The corner-sharing octahedral tilt angles range from 63-65°. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Rh(1) and one Se(1) atom. In the second Se site, Se(2) is bonded to three equivalent Rh(1) and one Se(2) atom to form distorted SeRh3Se tetrahedra that share corners with three equivalent Rh(1)Se6 octahedra and corners with three equivalent Se(2)Rh3Se tetrahedra. The corner-sharing octahedral tilt angles are 79°.
Rh3Se8 crystallizes in the trigonal R-3 space group. Rh(1) is bonded to two equivalent Se(2) and four equivalent Se(1) atoms to form RhSe6 octahedra that share corners with eight equivalent Rh(1)Se6 octahedra and corners with two equivalent Se(2)Rh3Se tetrahedra. The corner-sharing octahedral tilt angles range from 63-65°. Both Rh(1)-Se(2) bond lengths are 2.52 Å. There are two shorter (2.50 Å) and two longer (2.51 Å) Rh(1)-Se(1) bond lengths. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Rh(1) and one Se(1) atom. The Se(1)-Se(1) bond length is 2.41 Å. In the second Se site, Se(2) is bonded to three equivalent Rh(1) and one Se(2) atom to form distorted SeRh3Se tetrahedra that share corners with three equivalent Rh(1)Se6 octahedra and corners with three equivalent Se(2)Rh3Se tetrahedra. The corner-sharing octahedral tilt angles are 79°. The Se(2)-Se(2) bond length is 2.48 Å.