Selenium trioxide

Selenium trioxide[1] | Structural formula of the monomer as found in the gas phase | Space-filling model of the monomer as found in the gas phase

|

Identifiers

CAS Number

* 13768-86-0 N

3D model (JSmol)

* monomer: Interactive image
* cyclic tetramer: Interactive image

ChemSpider |

* 103019 Y

ECHA InfoCard | 100.033.972

PubChem CID

* 115128

CompTox Dashboard (EPA)

* DTXSID50895004

InChI

* InChI=1S/O3Se/c1-4(2)3 Y

Key: VFLXBUJKRRJAKY-UHFFFAOYSA-N Y

* InChI=1/O3Se/c1-4(2)3

Key: VFLXBUJKRRJAKY-UHFFFAOYAC

SMILES

* monomer: O=[Se](=O)=O

* cyclic tetramer: O=[Se]0(=O)O[Se](=O)(=O)O[Se](=O)(=O)O[Se](=O)(=O)O0

Properties

Chemical formula

| SeO3
Molar mass | 126.96 g/mol
Appearance  | white hygroscopic crystals
Density | 3.44 g/cm3
Melting point | 118.35 °C (245.03 °F; 391.50 K)
Boiling point | sublimes

Solubility in water

| very soluble
Structure

Crystal structure

| tetragonal
Hazards
GHS labelling:[3]

Pictograms

Signal word

| Danger

Hazard statements

| H301, H331, H373, H410
NFPA 704 (fire diamond)  |

Lethal dose or concentration (LD, LC):

LD50 (median dose)

| 7 mg/kg (rat, oral)
7.08 mg/kg (mouse, oral)
5.06 mg/kg (guinea pig, oral)
2.25 mg/kg (rabbit, oral)
13 mg/kg (horse, oral)[2]

LC50 (median concentration)

| 13 mg/kg (pig, oral)
9.9 mg/kg (cow, oral)
3.3 mg/kg (goat, oral)
3.3 mg/kg (sheep, oral)[2]

Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

N verify (what is YN ?)

Infobox references

Chemical compound

Selenium trioxide is the inorganic compound with the formula SeO3. It is white, hygroscopic solid. It is also an oxidizing agent and a Lewis acid. It is of academic interest as a precursor to Se(VI) compounds.[4]

## Preparation

[edit]

Selenium trioxide is difficult to prepare because it is unstable with respect to the dioxide:

2 SeO3 → 2 SeO2 \+ O2

It has been generated in a number of ways despite the fact that the dioxide does not combust under normal conditions.[4] One method entails dehydration of anhydrous selenic acid with phosphorus pentoxide at 150–160 °C. Another method is the reaction of liquid sulfur trioxide with potassium selenate.

SO3 \+ K2SeO4 → K2SO4 \+ SeO3

## Reactions

[edit]

In its chemistry SeO3 generally resembles sulfur trioxide, SO3, rather than tellurium trioxide, TeO3.[4] The substance reacts explosively with oxidizable organic compounds.[5]

At 120 °C SeO3 reacts with selenium dioxide to form the Se(VI)-Se(IV) compound diselenium pentaoxide:[6]

SeO3 \+ SeO2 → Se2O5

It reacts with selenium tetrafluoride to form selenoyl fluoride, the selenium analogue of sulfuryl fluoride

2SeO3 \+ SeF4 → 2SeO2F2 \+ SeO2

As with SO3 adducts are formed with Lewis bases such as pyridine, dioxane and ether.[4]

With lithium oxide and sodium oxide it reacts to form salts of SeVIO54− and SeVIO66−:[7] With Li2O, it gives Li4SeO5, containing the trigonal pyramidal anion SeVIO54− with equatorial bonds, 170.6–171.9 pm; and longer axial Se−O bonds of 179.5 pm. With Na2O it gives Na4SeO5, containing the square pyramidal SeVIO54−, with Se−O bond lengths ranging from range 172.9 → 181.5 pm, and Na12(SeO4)3(SeO6), containing octahedral SeVIO66−. SeVIO66− is the conjugate base of the unknown orthoselenic acid (Se(OH)6).

## Structure

[edit]

In the solid phase SeO3 consists of cyclic tetramers, with an 8 membered (Se−O)4 ring. Selenium atoms are 4-coordinate, bond lengths being Se−O bridging are 175 pm and 181 pm, non-bridging 156 and 154 pm.[7]

SeO3 in the gas phase consists of tetramers and monomeric SeO3 which is trigonal planar with an Se−O bond length of 168.78 pm.[8]

## References

[edit]

1. ^ Lide, David R. (1998). Handbook of Chemistry and Physics (87 ed.). Boca Raton, Florida: CRC Press. pp. 4–81. ISBN 0-8493-0594-2.
2. ^ a b "Selenium compounds (as Se)". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
3. ^ "C&L Inventory". echa.europa.eu. Retrieved 16 December 2021.
4. ^ a b c d Egon Wiberg, Arnold Frederick Holleman (2001) Inorganic Chemistry, Elsevier ISBN 0123526515
5. ^ Schmidt, Bornmann & Wilhelm 1963.
6. ^ Z. Žák "Crystal structure of diselenium pentoxide Se2O5" Zeitschrift für anorganische und allgemeine Chemie 1980, volume 460, pp. 81–85. doi:10.1002/zaac.19804600108
7. ^ a b Handbook of Chalcogen Chemistry: New Perspectives in Sulfur, Selenium and Tellurium, Francesco A. Devillanova, Royal Society of Chemistry, 2007, ISBN 9780854043668
8. ^ Brassington, N. J.; Edwards, H. G. M.; Long, D. A.; Skinner, M. (1978). "The pure rotational Raman spectrum of SeO3". Journal of Raman Spectroscopy. 7 (3): 158–160. Bibcode:1978JRSp....7..158B. doi:10.1002/jrs.1250070310. ISSN 0377-0486.

## Further reading

[edit]

* Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
* Schmidt, Prof. Dr. Max; Bornmann, Dr. P.; Wilhelm, Dr. Irmgard (1963-10-02). "The Chemistry of Selenium Trioxide". Angewandte Chemie International Edition in English. 2 (11): 691–692. doi:10.1002/anie.196306913.

* v
* t
* e

Selenium compounds

Se(−II)|

* Se2−
* H2Se
* Al2Se3
* Sb2Se3
* As2Se3
* Bi2Se3
* CdSe
* CaSe
* CSe2
* OCSe
* CrSe
* CoSe
* CuSe
* (CH3)2Se
* GaSe
* Ga2Se3
* GeSe
* In2Se3
* FeSe
* PbSe
* MgSe
* MnSe
* MnSe2
* HgSe
* MoSe2
* NiSe
* NbSe2
* NbSe3
* PxSey
* PuSe
* ReSe2
* Sm2Se3
* Ag2Se
* Na2Se
* SnSe
* TiSe2
* WSe2
* USe2
* ZnSe

Se(0,I)|

* Se3S5

Se(I)|

* Se2S6
* Se2Cl2
* C3H7NO2Se

Se(II)|

* SeBr2
* SeCl2
* SeS2

Se(IV)|

* SeO2−3
* SeBr4
* SeCl4
* SeF4
* SeO2
* SeS2
* SeOF2
* SeOCl2
* SeOBr2
* H2SeO3

Se(VI)|

* SeO2−4
* SeF6
* SeO3
* SeO2F2
* H2SeO4

Se(IV,VI)|

* SeO2−4 \+ SeO2−3

* v
* t
* e

Oxides

Mixed oxidation states|

* Antimony tetroxide (Sb2O4)
* Boron suboxide (B12O2)
* Carbon suboxide (C3O2)
* Chlorine perchlorate (Cl2O4)
* Chloryl perchlorate (Cl2O6)
* Cobalt(II,III) oxide (Co3O4)
* Dichlorine pentoxide (Cl2O5)
* Iron(II,III) oxide (Fe3O4)
* Lead(II,IV) oxide (Pb3O4)
* Manganese(II,III) oxide (Mn3O4)
* Mellitic anhydride (C12O9)
* Praseodymium(III,IV) oxide (Pr6O11)
* Silver(I,III) oxide (Ag2O2)
* Terbium(III,IV) oxide (Tb4O7)
* Tribromine octoxide (Br3O8)
* Triuranium octoxide (U3O8)

+1 oxidation state|

* Aluminium(I) oxide (Al2O)
* Copper(I) oxide (Cu2O)
* Caesium monoxide (Cs2O)
* Dibromine monoxide (Br2O)
* Dicarbon monoxide (C2O)
* Dichlorine monoxide (Cl2O)
* Gallium(I) oxide (Ga2O)
* Iodine(I) oxide (I2O)
* Lithium oxide (Li2O)
* Mercury(I) oxide (Hg2O)
* Nitrous oxide (N2O)
* Potassium oxide (K2O)
* Rubidium oxide (Rb2O)
* Silver oxide (Ag2O)
* Thallium(I) oxide (Tl2O)
* Sodium oxide (Na2O)
* Water (hydrogen oxide) (H2O)

+2 oxidation state|

* Aluminium(II) oxide (AlO)
* Barium oxide (BaO)
* Berkelium monoxide (BkO)
* Beryllium oxide (BeO)
* Boron monoxide (BO)
* Bromine monoxide (BrO)
* Cadmium oxide (CdO)
* Calcium oxide (CaO)
* Carbon monoxide (CO)
* Chlorine monoxide (ClO)
* Chromium(II) oxide (CrO)
* Cobalt(II) oxide (CoO)
* Copper(II) oxide (CuO)
* Dinitrogen dioxide (N2O2)
* Europium(II) oxide (EuO)
* Germanium monoxide (GeO)
* Iron(II) oxide (FeO)
* Iodine monoxide (IO)
* Lead(II) oxide (PbO)
* Magnesium oxide (MgO)
* Manganese(II) oxide (MnO)
* Mercury(II) oxide (HgO)
* Nickel(II) oxide (NiO)
* Nitric oxide (NO)
* Niobium monoxide (NbO)
* Palladium(II) oxide (PdO)
* Phosphorus monoxide (PO)
* Polonium monoxide (PoO)
* Protactinium monoxide (PaO)
* Radium oxide (RaO)
* Silicon monoxide (SiO)
* Strontium oxide (SrO)
* Sulfur monoxide (SO)
* Disulfur dioxide (S2O2)
* Thorium monoxide (ThO)
* Tin(II) oxide (SnO)
* Titanium(II) oxide (TiO)
* Vanadium(II) oxide (VO)
* Yttrium(II) oxide (YO)
* Zirconium monoxide (ZrO)
* Zinc oxide (ZnO)

+3 oxidation state|

* Actinium(III) oxide (Ac2O3)
* Aluminium oxide (Al2O3)
* Americium(III) oxide (Am2O3)
* Antimony trioxide (Sb2O3)
* Arsenic trioxide (As2O3)
* Berkelium(III) oxide (Bk2O3)
* Bismuth(III) oxide (Bi2O3)
* Boron trioxide (B2O3)
* Caesium sesquioxide (Cs2O3)
* Californium(III) oxide (Cf2O3)
* Cerium(III) oxide (Ce2O3)
* Chromium(III) oxide (Cr2O3)
* Cobalt(III) oxide (Co2O3)
* Dinitrogen trioxide (N2O3)
* Dysprosium(III) oxide (Dy2O3)
* Einsteinium(III) oxide (Es2O3)
* Erbium(III) oxide (Er2O3)
* Europium(III) oxide (Eu2O3)
* Gadolinium(III) oxide (Gd2O3)
* Gallium(III) oxide (Ga2O3)
* Gold(III) oxide (Au2O3)
* Holmium(III) oxide (Ho2O3)
* Indium(III) oxide (In2O3)
* Iron(III) oxide (Fe2O3)
* Lanthanum oxide (La2O3)
* Lutetium(III) oxide (Lu2O3)
* Manganese(III) oxide (Mn2O3)
* Neodymium(III) oxide (Nd2O3)
* Nickel(III) oxide (Ni2O3)
* Phosphorus trioxide (P4O6)
* Praseodymium(III) oxide (Pr2O3)
* Promethium(III) oxide (Pm2O3)
* Rhodium(III) oxide (Rh2O3)
* Samarium(III) oxide (Sm2O3)
* Scandium oxide (Sc2O3)
* Terbium(III) oxide (Tb2O3)
* Thallium(III) oxide (Tl2O3)
* Thulium(III) oxide (Tm2O3)
* Titanium(III) oxide (Ti2O3)
* Tungsten(III) oxide (W2O3)
* Vanadium(III) oxide (V2O3)
* Ytterbium(III) oxide (Yb2O3)
* Yttrium(III) oxide (Y2O3)

+4 oxidation state|

* Americium dioxide (AmO2)
* Berkelium(IV) oxide (BkO2)
* Bromine dioxide (BrO2)
* Californium dioxide (CfO2)
* Carbon dioxide (CO2)
* Carbon trioxide (CO3)
* Cerium(IV) oxide (CeO2)
* Chlorine dioxide (ClO2)
* Chromium(IV) oxide (CrO2)
* Curium(IV) oxide (CmO2)
* Dinitrogen tetroxide (N2O4)
* Germanium dioxide (GeO2)
* Iodine dioxide (IO2)
* Iridium dioxide (IrO2)
* Hafnium(IV) oxide (HfO2)
* Lead dioxide (PbO2)
* Manganese dioxide (MnO2)
* Molybdenum dioxide (MoO2)
* Neptunium(IV) oxide (NpO2)
* Nitrogen dioxide (NO2)
* Niobium dioxide (NbO2)
* Osmium dioxide (OsO2)
* Platinum dioxide (PtO2)
* Plutonium(IV) oxide (PuO2)
* Polonium dioxide (PoO2)
* Praseodymium(IV) oxide (PrO2)
* Protactinium(IV) oxide (PaO2)
* Rhenium(IV) oxide (ReO2)
* Rhodium(IV) oxide (RhO2)
* Ruthenium(IV) oxide (RuO2)
* Selenium dioxide (SeO2)
* Silicon dioxide (SiO2)
* Sulfur dioxide (SO2)
* Technetium(IV) oxide (TcO2)
* Tellurium dioxide (TeO2)
* Terbium(IV) oxide (TbO2)
* Thorium dioxide (ThO2)
* Tin dioxide (SnO2)
* Titanium dioxide (TiO2)
* Tungsten(IV) oxide (WO2)
* Uranium dioxide (UO2)
* Vanadium(IV) oxide (VO2)
* Zirconium dioxide (ZrO2)

+5 oxidation state|

* Antimony pentoxide (Sb2O5)
* Arsenic pentoxide (As2O5)
* Bismuth pentoxide (Bi2O5)
* Dinitrogen pentoxide (N2O5)
* Niobium pentoxide (Nb2O5)
* Phosphorus pentoxide (P2O5)
* Protactinium(V) oxide (Pa2O5)
* Tantalum pentoxide (Ta2O5)
* Tungsten pentoxide (W2O5)
* Vanadium(V) oxide (V2O5)

+6 oxidation state|

* Chromium trioxide (CrO3)
* Molybdenum trioxide (MoO3)
* Polonium trioxide (PoO3)
* Rhenium trioxide (ReO3)
* Selenium trioxide (SeO3)
* Sulfur trioxide (SO3)
* Tellurium trioxide (TeO3)
* Tungsten trioxide (WO3)
* Uranium trioxide (UO3)
* Xenon trioxide (XeO3)

+7 oxidation state|

* Dichlorine heptoxide (Cl2O7)
* Manganese heptoxide (Mn2O7)
* Rhenium(VII) oxide (Re2O7)
* Technetium(VII) oxide (Tc2O7)

+8 oxidation state|

* Iridium tetroxide (IrO4)
* Osmium tetroxide (OsO4)
* Ruthenium tetroxide (RuO4)
* Xenon tetroxide (XeO4)
* Hassium tetroxide (HsO4)

Related|

* Oxocarbon
* Suboxide
* Oxyanion
* Ozonide
* Peroxide
* Superoxide
* Oxypnictide

Oxides are sorted by oxidation state. Category:Oxides
*[CID]: Compound ID
*[EPA]: U.S. Environmental Protection Agency
*[H301]: H301: Toxic if swallowed
*[H331]: H331: Toxic if inhaled
*[H373]: H373: May cause damage to organs through prolonged or repeated exposure
*[H410]: H410: Very toxic to aquatic life with long lasting effects
*[v]: View this template
*[t]: Discuss this template
*[e]: Edit this template