DOE OSTI2020
Rh3Se8 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are two inequivalent Rh+3.33+ sites. In the first Rh+3.33+ site, Rh+3.33+ is bonded to six Se+1.25- atoms to form RhSe6 octahedra that share corners with eight RhSe6 octahedra and corners with two equivalent SeRh3Se tetrahedra. The corner-sharing octahedra tilt angles range from 63–66°. There are a spread of Rh–Se bond distances ranging from 2.49–2.57 Å. In the second Rh+3.33+ site, Rh+3.33+ is bonded to six Se+1.25- atoms to form corner-sharing RhSe6 octahedra. The corner-sharing octahedra tilt angles range from 63–66°. There are a spread of Rh–Se bond distances ranging from 2.52–2.54 Å. There are four inequivalent Se+1.25- sites. In the first Se+1.25- site, Se+1.25- is bonded to three Rh+3.33+ and one Se+1.25- atom to form distorted SeRh3Se tetrahedra that share corners with two equivalent RhSe6 octahedra and corners with three equivalent SeRh3Se tetrahedra. The corner-sharing octahedra tilt angles range from 79–80°. The Se–Se bond length is 2.46 Å. In the second Se+1.25- site, Se+1.25- is bonded in a 2-coordinate geometry to two equivalent Rh+3.33+ and one Se+1.25- atom. In the third Se+1.25- site, Se+1.25- is bonded in a 3-coordinate geometry to two Rh+3.33+ and one Se+1.25- atom. The Se–Se bond length is 2.44 Å. In the fourth Se+1.25- site, Se+1.25- is bonded in a 3-coordinate geometry to two Rh+3.33+ and one Se+1.25- atom. The Se–Se bond length is 2.45 Å.