Tin(II) oxide

Tin(II) oxide
IUPAC name

Tin(II) oxide
Other names

Stannous oxide, tin monoxide
Identifiers
CAS number 21651-19-4 Y
RTECS number XQ3700000
Properties
Molecular formula SnO
Molar mass 134.71 g/mol
Appearance black or red powder when anhydrous, white when hydrated
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
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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

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 with a dim green flame to form SnO2.[2]

2 SnO + O2 → 2 SnO2

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]

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]

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]

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