DOE OSTI2020
IrSe3 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are seven inequivalent Ir5+ sites. In the first Ir5+ site, Ir5+ is bonded to six Se+1.67- atoms to form IrSe6 octahedra that share corners with four IrSe6 octahedra and corners with two equivalent IrSe5 square pyramids. The corner-sharing octahedra tilt angles range from 63–67°. There are a spread of Ir–Se bond distances ranging from 2.48–2.54 Å. In the second Ir5+ site, Ir5+ is bonded to six Se+1.67- atoms to form corner-sharing IrSe6 octahedra. The corner-sharing octahedra tilt angles range from 63–66°. There are a spread of Ir–Se bond distances ranging from 2.50–2.56 Å. In the third Ir5+ site, Ir5+ is bonded to six Se+1.67- atoms to form IrSe6 octahedra that share corners with four IrSe6 octahedra and corners with two equivalent IrSe5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 63–67°. There are a spread of Ir–Se bond distances ranging from 2.49–2.54 Å. In the fourth Ir5+ site, Ir5+ is bonded to five Se+1.67- atoms to form IrSe5 trigonal bipyramids that share corners with two equivalent IrSe6 octahedra and corners with two equivalent IrSe5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 60–63°. There are a spread of Ir–Se bond distances ranging from 2.43–2.49 Å. In the fifth Ir5+ site, Ir5+ is bonded to five Se+1.67- atoms to form corner-sharing IrSe5 trigonal bipyramids. There are a spread of Ir–Se bond distances ranging from 2.36–2.52 Å. In the sixth Ir5+ site, Ir5+ is bonded to five Se+1.67- atoms to form IrSe5 square pyramids that share corners with two equivalent IrSe6 octahedra and corners with two equivalent IrSe5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 60–63°. There are a spread of Ir–Se bond distances ranging from 2.42–2.49 Å. In the seventh Ir5+ site, Ir5+ is bonded to six Se+1.67- atoms to form corner-sharing IrSe6 octahedra. The corner-sharing octahedra tilt angles range from 63–67°. There are four shorter (2.51 Å) and two longer (2.55 Å) Ir–Se bond lengths. There are twenty-one inequivalent Se+1.67- sites. In the first Se+1.67- site, Se+1.67- is bonded in a 3-coordinate geometry to two Ir5+ and one Se+1.67- atom. The Se–Se bond length is 2.40 Å. In the second Se+1.67- site, Se+1.67- is bonded in a 2-coordinate geometry to two Ir5+ and one Se+1.67- atom. The Se–Se bond length is 2.50 Å. In the third Se+1.67- site, Se+1.67- is bonded in a 2-coordinate geometry to one Ir5+ and one Se+1.67- atom. The Se–Se bond length is 2.40 Å. In the fourth Se+1.67- site, Se+1.67- is bonded in a 2-coordinate geometry to two Ir5+ and one Se+1.67- atom. The Se–Se bond length is 2.47 Å. In the fifth Se+1.67- site, Se+1.67- is bonded in a 2-coordinate geometry to two Ir5+ and one Se+1.67- atom. The Se–Se bond length is 2.46 Å. In the sixth Se+1.67- site, Se+1.67- is bonded in a 2-coordinate geometry to two Ir5+ and one Se+1.67- atom. The Se–Se bond length is 2.48 Å. In the seventh Se+1.67- site, Se+1.67- is bonded in a 2-coordinate geometry to two Ir5+ atoms. In the eighth Se+1.67- site, Se+1.67- is bonded in a 4-coordinate geometry to three Ir5+ and one Se+1.67- atom. The Se–Se bond length is 2.53 Å. In the ninth Se+1.67- site, Se+1.67- is bonded in a 2-coordinate geometry to two Ir5+ atoms. In the tenth Se+1.67- site, Se+1.67- is bonded in a 4-coordinate geometry to three Ir5+ and one Se+1.67- atom. In the eleventh Se+1.67- site, Se+1.67- is bonded in a 2-coordinate geometry to two Ir5+ atoms. In the twelfth Se+1.67- site, Se+1.67- is bonded in a 2-coordinate geometry to two Ir5+ and one Se+1.67- atom. In the thirteenth Se+1.67- site, Se+1.67- is bonded in a 2-coordinate geometry to two Ir5+ and one Se+1.67- atom. In the fourteenth Se+1.67- site, Se+1.67- is bonded in a 2-coordinate geometry to two Ir5+ and one Se+1.67- atom. In the fifteenth Se+1.67- site, Se+1.67- is bonded in a 2-coordinate geometry to two Ir5+ atoms. In the sixteenth Se+1.67- site, Se+1.67- is bonded in a 2-coordinate geometry to one Ir5+ and one Se+1.67- atom. In the seventeenth Se+1.67- site, Se+1.67- is bonded in a 2-coordinate geometry to two Ir5+ and one Se+1.67- atom. In the eighteenth Se+1.67- site, Se+1.67- is bonded in a 3-coordinate geometry to two Ir5+ and one Se+1.67- atom. In the nineteenth Se+1.67- site, Se+1.67- is bonded in a distorted single-bond geometry to one Ir5+ atom. In the twentieth Se+1.67- site, Se+1.67- is bonded in a distorted single-bond geometry to one Ir5+ atom. In the twenty-first Se+1.67- site, Se+1.67- is bonded in a distorted single-bond geometry to one Ir5+ atom.