Tin(II) oxide

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Tin(II) oxide
PbO structure.png
IUPAC name
Other names Stannous oxide
Identifiers
CAS number 21651-19-4 Yes check.svgY
RTECS number XQ3700000
Properties
Molecular formula SnO
Molar mass 134.71 g/mol
Appearance black powder
Density 6.45 g/cm3
Melting point

1080 °C (decomp)[1]
Solubility in water insoluble
Structure
Crystal structure tetragonal
Hazards
MSDS ICSC 0956
EU Index Not listed
Flash point Non-flammable
Related compounds
Other anions Tin sulfide
Tin selenide
Tin telluride
Other cations Carbon monoxide
Silicon monoxide
Germanium(II) oxide
Lead(II) oxide
Related tin oxides Tin dioxide
 Yes check.svgY (what is this?)  (verify)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Tin(II) oxide (stannous oxide) is a compound of tin and oxygen where tin has the oxidation state of +2. There are two forms, a stable blue-black form and a metastable red form.

Contents

[edit] Preparation and reactions

Blue-black SnO can be prepared by heating the tin(II) oxide hydrate, SnO.xH2O (x<1) precipitated when a tin(II) salt is reacted with an alkali hydroxide such as NaOH.[2] Metastable, red SnO can be prepared by gentle heating of the precipitate produced by the action of aqueous ammonia on a tin(II) salt.[2] SnO may be prepared as a pure substance in the laboratory, by controlled heating of tin(II) oxalate (stannous oxalate) in the absence of air.[3]

SnC2O4 → SnO + CO2 + CO

Tin(II) oxide burns in air to form SnO2.[2]When heated in an inert atmosphere initially disproportionation occurs giving Sn metal and Sn3O4 which further reacts to give SnO2 and Sn metal.[2]

4SnO → Sn3O4 + Sn
Sn3O4 → 2SnO2 + Sn

SnO is amphoteric, dissolving in strong acid to give tin(II) salts and in strong base to give stannites containing Sn(OH)3−.[2] It also dissolves in strong acid solutions to give the ionic complexes Sn(OH2)32+ and Sn(OH)(OH2)2+, and in less acid solutions to give Sn3(OH)42+.[2] Note that anhydrous stannites, e.g. K2Sn2O3, K2SnO2 are also known.[4][5][6] SnO is a reducing agent and this appears to its role in the manufacture of so-called "copper ruby glass".[7]

[edit] Structure

Black, α-SnO adopts the tetragonal PbO layer structure containing four coordinate square pyramidal tin atoms.[8]. This form is found in nature as the rare mineral romarchite.[9] The asymmetry is usually simply ascribed to a sterically active lone pair, however electron density calculations show that the asymmetry is caused by an antibonding interaction of the Sn(5s) and the O(2p) orbitals.[10]
Non-stoichiometry has been observed in SnO.[11]

The electronic band gap has been measured between 2.5eV and 3eV.[12]

[edit] Uses

The dominant use of stannous oxide is as a precursor in manufacturing of other, typically divalent, tin compounds or salts. Stannous oxide may also be employed as a reducing agent and in the creation of ruby glass. It has a minor use as an esterification catalyst.

Cerium(III) oxide in ceramic form, together with Tin(II) oxide (SnO) is used for illumination with UV light[13].

[edit] References

  1. ^ Tin and Inorganic Tin Compounds: Concise International Chemical Assessment Document 65, (2005), World Health Organization
  2. ^ a b c d e f Egon Wiberg, Arnold Frederick Holleman (2001) Inorganic Chemistry, Elsevier ISBN 0123526515
  3. ^ Satya Prakash (2000),Advanced Inorganic Chemistry: V. 1, S. Chand, ISBN 8121902630
  4. ^ The First Oxostannate(II): K2Sn2O3, M Braun, R. Hoppe, Angewandte Chemie International Edition in English, 17, 6, 449 - 450, doi:10.1002/anie.197804491
  5. ^ Über Oxostannate(II). III. K2Sn2O3, Rb2Sn2O3 und Cs2Sn2O3 - ein Vergleich, R. M. Braun, R. Hoppe, Zeitschrift für anorganische und allgemeine Chemie, 485, 1, 15 - 22, doi:10.1002/zaac.19824850103
  6. ^ R M Braun R Hoppe Z. Naturforsch. (1982), 37B, 688-694
  7. ^ Colour development in copper ruby alkali silicate glasses. Part I: The impact of tin oxide, time and temperature ,Bring, T., Jonson, B., Kloo, L. Rosdahl, J , Wallenberg, R., Glass Technology, Eur. J. Glass Science & Technology, Part A, 48 , 2 , 101-108 ( 2007)
  8. ^ Wells A.F. (1984) Structural Inorganic Chemistry 5th edition Oxford Science Publications ISBN 0-19-855370-6
  9. ^ On type romarchite and hydroromarchite from Boundary Falls, Ontario, and notes on other occurrences, Robert A. Ramik,, Robert M. Organ, Joseph A. Mandarino, The Canadian Mineralogist; June 2003; v. 41; no. 3;. 649-657; doi:10.2113/gscanmin.41.3.649
  10. ^ Electronic structures of rocksalt, litharge, and herzenbergite SnO by density functional theory, A. Walsh, G.W. Watson, Phys. Rev. B 70, 235114 (2004)doi:10.1103/PhysRevB.70.235114
  11. ^ Cation nonstoichiometry in tin-monoxide-phase Sn1-δO with tweed microstructure, Moreno, M. S.; Varela, A.; Otero-Díaz, L. C., Physical Review B (Condensed Matter),56, 9,(1997), 5186-5192, doi:10.1103/PhysRevB.56.5186
  12. ^ Science and Technology of Chemiresistor Gas Sensors By Dinesh K. Aswal, Shiv K. Gupta (2006), Nova Publishers, ISBN 1600215149
  13. ^ Spectral Studies of New Luminophors for Dental Porcelain


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