Arsenic trisulfide
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| Names | |
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| Preferred IUPAC name
Arsenic trisulfide | |
Other names
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| Identifiers | |
3D model (JSmol)
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| ChemSpider | |
| ECHA InfoCard | 100.013.744 |
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PubChemCID
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| UNII | |
CompTox Dashboard(EPA)
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| Properties | |
| As2S3 | |
| Molar mass | 246.02g·mol−1 |
| Appearance | yellow or orange crystals |
| Density | 3.43 g/cm3 |
| Melting point | 310 °C (590 °F; 583 K) |
| Boiling point | 707 °C (1,305 °F; 980 K) |
| insoluble | |
| Solubility | soluble inammonia |
| −70.0·10−6cm3/mol | |
| Structure[1] | |
| monoclinic | |
| P21/n(No. 11) | |
a= 1147.5(5) pm,b= 957.7(4) pm,c= 425.6(2) pm α = 90°, β = 90.68(8)°, γ = 90°
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| pyramidal (As) | |
| Hazards | |
| GHSlabelling:[3][4] | |
 
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| Danger | |
| H300,H331,H400,H411 | |
| NFPA 704(fire diamond) | |
| NIOSH(US health exposure limits): | |
PEL(Permissible)
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[1910.1018] TWA 0.010 mg/m3[2] |
REL(Recommended)
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Ca C 0.002 mg/m3[15-minute][2] |
IDLH(Immediate danger)
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Ca [5 mg/m3(as As)][2] |
| Related compounds | |
Related compounds
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Except where otherwise noted, data are given for materials in theirstandard state(at 25 °C [77 °F], 100 kPa).
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Arsenic trisulfideis theinorganic compoundwith the formulaAs2S3.It is a dark yellow solid that is insoluble in water. It also occurs as the mineralorpiment(Latin: auripigmentum), which has been used as a pigment called King's yellow. It is produced in the analysis of arsenic compounds. It is a group V/VI,intrinsicp-typesemiconductorand exhibits photo-induced phase-change properties.[clarification needed]
Structure[edit]
As2S3occurs both in crystalline and amorphous forms. Both forms feature polymeric structures consisting oftrigonal pyramidalAs(III) centres linked by sulfide centres. The sulfide centres are two-fold coordinated to two arsenic atoms. In the crystalline form, the compound adopts a ruffled sheet structure.[5]The bonding between the sheets consists ofvan der Waals forces.The crystalline form is usually found in geological samples. AmorphousAs2S3does not possess a layered structure but is more highly cross-linked. Like otherglasses,there is no medium or long-range order, but the first co-ordination sphere is well defined.As2S3is a goodglass formerand exhibits a wide glass-forming region in itsphase diagram.
Properties[edit]
It is asemiconductor,with a directband gapof 2.7 eV.[6]The wide band gap makes it transparent toinfraredlight between 620 nm and 11 μm.
Synthesis[edit]
From the elements[edit]
AmorphousAs2S3is obtained via the fusion of the elements at 390 °C. Rapid cooling of the reaction melt gives a glass. The reaction can be represented with the chemical equation:
- 2 As + 3 S → As2S3
Aqueous precipitation[edit]
As2S3forms when aqueous solutions containing As(III) are treated withH2S.Arsenic was in the past analyzed and assayed by this reaction, which results in theprecipitationofAs2S3,which is then weighed.As2S3can even be precipitated in 6MHCl.As2S3is so insoluble that it is not toxic.
Reactions[edit]
Upon heating in a vacuum, polymericAs2S3"cracks" to give a mixture of molecular species, including molecularAs4S6.[7][8]As4S6adopts theadamantanegeometry, like that observed forP4O6andAs4O6.When a film of this material is exposed to an external energy source such as thermal energy (via thermal annealing[9]), electromagnetic radiation (i.e. UV lamps, lasers,[10]electron beams)[11]), As4S6polymerizes:
- 2 (As2S3)n⇌nAs4S6
As2S3characteristically dissolves upon treatment with aqueous solutions containingsulfideions.[clarification needed]The dissolved arsenic species is the pyramidaltrithioarseniteanionAsS3−3:
- As2S3+ 6 NaSH → 2 AsS3−3+ 3 H2S[clarification needed]
As2S3is the anhydride of the hypothetical trithioarsenous acid,As(SH)3.Upon treatment withpolysulfideions,As2S3dissolves to give a variety of species containing both S–S and As–S bonds. One derivative isS7As−S−,an eight-membered ring that contains 7 S atoms and 1 As atom, and anexocyclicsulfidocenter attached to the As atom.As2S3also dissolves in strongly alkaline solutions to give a mixture ofAsS3−3andAsO3−3.[12]
"Roasting"As2S3in air gives volatile, toxic derivatives, this conversion being one of the hazards associated with the refining of heavy metalores:
- 2 As2S3+ 9 O2→ As4O6+ 6 SO2
Contemporary uses[edit]
As an inorganic photoresist[edit]
Due to its highrefractive indexof 2.45 and its largeKnoop hardnesscompared to organicphotoresists,As2S3has been investigated for the fabrication ofphotonic crystalswith a full-photonic band-gap. Advances in laser patterning techniques such as three-dimensional direct laser writing (3-D DLW) and chemical wet-etching chemistry,has allowed this material to be used as a photoresist to fabricate 3-D nanostructures.[13][14]
As2S3has been investigated for use as a high resolution photoresist material since the early 1970s,[15][16]using aqueous etchants. Although these aqueous etchants allowed for low-aspect ratio 2-D structures to be fabricated, they do not allow for the etching of high aspect ratio structures with 3-D periodicity. Certain organic reagents, used in organic solvents, permit the high-etch selectivity required to produce high-aspect ratio structures with 3-D periodicity.
Medical applications[edit]
As2S3andAs4S4have been investigated as treatments for acute promyelocytic leukemia (APL).
For IR-transmitting glasses[edit]
Arsenic trisulfide manufactured intoamorphousform is used as achalcogenide glassforinfraredoptics.It is transparent for light between wavelengths of 620 nm and 11 μm. The arsenic trisulfide glass is more resistant to oxidation than crystalline arsenic trisulfide, which minimizes toxicity concerns.[17]It can be also used as anacousto-opticmaterial.
Arsenic trisulfide was used for the distinctive eight-sided conical nose over the infra-red seeker of thede Havilland Firestreakmissile.
Role in ancient artistry[edit]
The ancient Egyptians reportedly used orpiment, natural or synthetic, as a pigment in artistry and cosmetics.
Miscellaneous[edit]
Arsenic trisulfide is also used as atanningagent. It was formerly used withindigo dyefor the production of pencil blue, which allowed dark blue hues to be added to fabric via pencil or brush.
Precipitation of arsenic trisulfide is used as an analytical test for presence of dissimilatory arsenic-reducing bacteria (DARB).[18]
Safety[edit]
As2S3is so insoluble that its toxicity is low. Aged samples can contain substantial amounts of arsenic oxides, which are soluble and therefore highly toxic.
Natural occurrence[edit]
Orpiment is found in volcanic environments, often together with other arsenic sulfides, mainlyrealgar.It is sometimes found in low-temperature hydrothermal veins, together with some other sulfide and sulfosalt minerals.
References[edit]
- ^Mullen, D. J. E.; Nowacki, W (1972),"Refinement of the crystal structures of realgar, AsS and orpiment, As2S3"(PDF),Z. Kristallogr.,136(1–2): 48–65,doi:10.1524/zkri.1972.136.1-2.48.
- ^abcNIOSH Pocket Guide to Chemical Hazards."#0038".National Institute for Occupational Safety and Health(NIOSH).
- ^Index no. 033-002-00-5 of Annex VI, Part 3, toRegulation (EC) No 1272/2008 of the European Parliament and of the Council of 16 December 2008 on classification, labelling and packaging of substances and mixtures, amending and repealing Directives 67/548/EEC and 1999/45/EC, and amending Regulation (EC) No 1907/2006.OJEUL353, 31.12.2008, pp 1–1355 at p 427.
- ^"Arsenic, inorganic compounds (as As)",29 C.F.R. § 1910.1018,58 FR 35310, June 30, 1993, as amended."Arsenic (inorganic compounds, as As)",Pocket Guide to Chemical Hazards,U.S. Department of Health and Human Services (NIOSH) Publication No. 2005-149, Washington, DC: Government Printing Office, 2005,ISBN9780160727511.
- ^Wells, A.F. (1984). Structural Inorganic Chemistry, Oxford: Clarendon Press.ISBN0-19-855370-6.
- ^Arsenic sulfide (As2S3)
- ^Martin, T.P. (1983). "Arsenic sulfide clusters".Solid State Communications.47(2). Elsevier BV: 111–114.doi:10.1016/0038-1098(83)90620-8.ISSN0038-1098.
- ^Hammam, M.; Santiago, J.J. (1986). "Evidence for As4S6molecule as a structural model for amorphous arsenic sulfide from mass spectrometric analysis ".Solid State Communications.59(11). Elsevier BV: 725–727.doi:10.1016/0038-1098(86)90705-2.ISSN0038-1098.
- ^Street, R. A.;Nemanich, R. J.;Connell, G. A. N. (1978-12-15). "Thermally induced effects in evaporated chalcogenide films. II. Optical absorption".Physical Review B.18(12). American Physical Society (APS): 6915–6919.doi:10.1103/physrevb.18.6915.ISSN0163-1829.
- ^Zoubir, Arnaud; Richardson, Martin; Rivero, Clara; Schulte, Alfons; Lopez, Cedric; et al. (2004-04-01). "Direct femtosecond laser writing of waveguides in As2S3thin films ".Optics Letters.29(7). The Optical Society: 748–50.doi:10.1364/ol.29.000748.ISSN0146-9592.PMID15072379.
- ^Nordman, Olli; Nordman, Nina; Peyghambarian, Nasser (1998). "Electron beam induced changes in the refractive index and film thickness of amorphous AsxS100−xand AsxSe100−xfilms ".Journal of Applied Physics.84(11). AIP Publishing: 6055–6058.doi:10.1063/1.368915.ISSN0021-8979.
- ^Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001.ISBN0-12-352651-5.
- ^Wong, S.; Deubel, M.; Pérez-Willard, F.; John, S.; Ozin, G. A.; Wegener, M.; von Freymann, G. (2006-02-03)."Direct Laser Writing of Three- Dimensional Photonic Crystals with a Complete Photonic Bandgap in Chalcogenide Glasses".Advanced Materials.18(3). Wiley: 265–269.doi:10.1002/adma.200501973.ISSN0935-9648.S2CID53527218.
- ^Wong, Sean H.; Thiel, Michael; Brodersen, Peter; Fenske, Dieter; Ozin, Geoffrey A.; Wegener, Martin; von Freymann, Georg (2007). "Highly Selective Wet Etch for High-Resolution Three-Dimensional Nanostructures in Arsenic Sulfide All-Inorganic Photoresist".Chemistry of Materials.19(17). American Chemical Society (ACS): 4213–4221.doi:10.1021/cm070756y.ISSN0897-4756.
- ^Stoycheva, Rumiana; Simidchieva, Penka; Buroff, Atanas (1987). "Temperature dependence of the photodissociation of a-As2S3".Journal of Non-Crystalline Solids.90(1–3). Elsevier BV: 541–544.doi:10.1016/s0022-3093(87)80482-9.ISSN0022-3093.
- ^Zenkin, S. A.; Mamedov, S. B.; Mikhailov, M. D.; Turkina, E. Yu.; Yusupov, I. Yu. Glass Phys. Chem. 1997, 5, pp 393-399.
- ^Material Safety Data SheetArchivedOctober 7, 2007, at theWayback Machine
- ^Linping Kuai, Arjun A. Nair, and Martin F. Polz "Rapid and Simple Method for the Most-Probable-Number Estimation of Arsenic-Reducing Bacteria" Appl Environ Microbiol. 2001, vol. 67, 3168–3173.doi:10.1128/AEM.67.7.3168-3173.2001.
Further reading[edit]
- "Arsenic and arsenic compounds",Overall Evaluations of Carcinogenicity: An Updating ofIARC MonographsVolumes 1 to 42(PDF),IARC Monographs on the Evaluation of Carcinogenic Risks to Humans Supplement 7, Lyon, France: International Agency for Research on Cancer, 1987, pp. 100–6,ISBN92-832-1411-0."Arsenic in Drinking Water",Some Drinking-water Disinfectants and Contaminants, including Arsenic(PDF),IARC Monographs on the Evaluation of Carcinogenic Risks to Humans 84, Lyon, France: International Agency for Research on Cancer, 2004, pp. 39–267,ISBN92-832-1284-3.
- "Arsenic Compounds, Inorganic",Report on Carcinogens, Eleventh Edition(PDF), U.S. Department of Health and Human Services, Public Health Service, National Toxicology Program, 2005.