Scandium(III) sulfide is a chemical compound of scandium and sulfur with the chemical formula Sc<sub>2</sub>S<sub>3</sub>. It is a yellow solid.
The crystal structure of Sc<sub>2</sub>S<sub>3</sub> is closely related to that of sodium chloride, in that it is based on a cubic close packed array of anions. Whereas NaCl has all the octahedral interstices in the anion lattice occupied by cations, Sc<sub>2</sub>S<sub>3</sub> has one third of them vacant. The vacancies are ordered, but in a very complicated pattern, leading to a large, orthorhombic unit cell belonging to the space group Fddd.
Metal sulfides are usually prepared by heating mixtures of the two elements, but in the case of scandium, this method yields scandium monosulfide, ScS. Sc<sub>2</sub>S<sub>3</sub> can be prepared by heating scandium(III) oxide under flowing hydrogen sulfide in a graphite crucible to 1550 ðC or above for 2âÂÂ3 hours. The crude product is then purified by chemical vapor transport at 950 ðC using iodine as the transport agent.
Scandium(III) sulfide can be prepared by reacting scandium(III) chloride with dry hydrogen sulfide at elevated temperature:
Above 1100 ðC, Sc<sub>2</sub>S<sub>3</sub> loses sulfur, forming nonstoichiometric compounds such as Sc<sub>1.37</sub>S<sub>2</sub>.