Scandium(III) sulfide

Scandium(III) sulfide

Names
Other names scandium sesquisulfide
Identifiers
CAS Number	12166-29-9
Jmol interactive 3D	Image
InChI InChI=1S/3S.2Sc
SMILES S=[Sc]S[Sc]=S
Properties
Chemical formula	Sc2S3
Molar mass	186.11 g/mol
Appearance	yellow crystals
Density	2.91 g/cm^3, solid
Melting point	1,775 °C (3,227 °F; 2,048 K)
Structure
Crystal structure	orthorhombic
Hazards
EU classification (DSD)	not listed
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Scandium(III) sulfide is a chemical compound of scandium and sulfur with the chemical formula Sc₂S₃. It is a yellow solid.

Structure

The crystal structure of Sc₂S₃ 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, Sc₂S₃ 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.^[1]

Synthesis

Metal sulfides are usually prepared by heating mixtures of the two elements, but in the case of scandium, this method yields scandium monosulfide, ScS. Sc₂S₃ can be prepared by heating scandium(III) oxide under flowing hydrogen sulfide in a graphite crucible to 1550 °C or above for 2–3 hours. The crude product is then purified by chemical vapor transport at 950 °C using iodine as the transport agent.^[1]

Sc₂O₃ + 3H₂S → Sc₂S₃ + 3H₂O

Reactivity

Above 1100 °C, Sc₂S₃ loses sulfur, forming nonstoichiometric compounds such as Sc_1.37S₂.^[1]

References

1. Dismukes, J. P.; White, J. G. (1964). "The Preparation, Properties, and Crystal Structures of Some Scandium Sulfides in the Range Sc₂S₃-ScS". Inorg. Chem. 3 (9): 1220–1228. doi:10.1021/ic50019a004.