Tin(II) oxide

Tin(II) oxide
Names
	IUPAC name Tin(II) oxide
	Other names Stannous oxide; Tin monoxide
Identifiers
CAS Number	21651-19-4 ;
3D model (JSmol)	Interactive image;
ECHA InfoCard	100.040.439
EC Number	244-499-5;
PubChem CID	88989;
RTECS number	XQ3700000;
UNII	JB2MV9I3LS ;
CompTox Dashboard (EPA)	DTXSID2066723 ;
	InChI InChI=1S/O.Sn;
	SMILES O=[Sn];
Properties
Chemical formula	SnO
Molar mass	134.709 g/mol
Appearance	black or red powder when anhydrous, white when hydrated
Density	6.45 g/cm3
Melting point	1,080 °C (1,980 °F; 1,350 K)
Solubility in water	insoluble
Magnetic susceptibility (χ)	−19.0·10−6 cm3/mol
Structure
Crystal structure	tetragonal
Thermochemistry
Std molar; entropy (S⦵298)	56 J·mol−1·K−1
Std enthalpy of; formation (ΔfH⦵298)	−285 kJ·mol−1
Hazards
Flash point	Non-flammable
	NIOSH (US health exposure limits):
PEL (Permissible)	none
REL (Recommended)	TWA 2 mg/m3
IDLH (Immediate danger)	N.D.
Safety data sheet (SDS)	ICSC 0956
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
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Tin(II) oxide (stannous oxide) is a compound with the formula SnO. It is composed 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.

Preparation and reactions

Blue-black SnO can be produced 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.^[4]
Metastable, red SnO can be prepared by gentle heating of the precipitate produced by the action of aqueous ammonia on a tin(II) salt.^[4]
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 or under a CO₂ atmosphere. This method is also applied to the production of ferrous oxide and manganous oxide.^[5]^[6]

SnC₂O₄·2H₂O → SnO + CO₂ + CO + 2 H₂O

Tin(II) oxide burns in air with a dim green flame to form SnO₂.^[4]

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.^[4]

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⁻.^[4] It can be dissolved 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⁺.^[4] Note that anhydrous stannites, e.g. K₂Sn₂O₃, K₂SnO₂ are also known.^[7]^[8]^[9] SnO is a reducing agent and is thought to reduce copper(I) to metallic clusters in the manufacture of so-called "copper ruby glass".^[10]

Structure

Black, α-SnO adopts the tetragonal PbO layer structure containing four coordinate square pyramidal tin atoms.^[11] This form is found in nature as the rare mineral romarchite.^[12] 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.^[13] The electronic structure and chemistry of the lone pair determines most of the properties of the material.^[14]

Non-stoichiometry has been observed in SnO.^[15]

The electronic band gap has been measured between 2.5eV and 3eV.^[16]

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.^[17] 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.^[18]

References

^ Tin and Inorganic Tin Compounds: Concise International Chemical Assessment Document 65, (2005), World Health Organization
^ ^a ^b Zumdahl, Steven S. (2009). Chemical Principles 6th Ed. Houghton Mifflin Company. p. A23. ISBN 978-0-618-94690-7.
^ ^a ^b ^c NIOSH Pocket Guide to Chemical Hazards. "#0615". National Institute for Occupational Safety and Health (NIOSH).
^ ^a ^b ^c ^d ^e ^f Egon Wiberg, Arnold Frederick Holleman (2001) Inorganic Chemistry, Elsevier ISBN 0-12-352651-5
^ Satya Prakash (2000),Advanced Inorganic Chemistry: V. 1, S. Chand, ISBN 81-219-0263-0
^ Arthur Sutcliffe (1930) Practical Chemistry for Advanced Students (1949 Ed.), John Murray - London.
^ Braun, Rolf Michael; Hoppe, Rudolf (1978). "The First Oxostannate(II): K₂Sn₂O₃". Angewandte Chemie International Edition in English. 17 (6): 449–450. doi:10.1002/anie.197804491.
^ Braun, R. M.; Hoppe, R. (1982). "Über Oxostannate(II). III. K₂Sn₂O₃, Rb₂Sn₂O₃ und Cs₂Sn₂O₃ - ein Vergleich". Zeitschrift für Anorganische und Allgemeine Chemie. 485: 15–22. doi:10.1002/zaac.19824850103.
^ R M Braun R Hoppe Z. Naturforsch. (1982), 37B, 688-694
^ Bring, T.; Jonson, B.; Kloo, L.; Rosdahl, J; Wallenberg, R. (2007), "Colour development in copper ruby alkali silicate glasses. Part I: The impact of tin oxide, time and temperature", Glass Technology, Eur. J. Glass Science & Technology, Part A, 48 (2): 101–108, ISSN 1753-3546
^ Wells A.F. (1984) Structural Inorganic Chemistry 5th edition Oxford Science Publications ISBN 0-19-855370-6
^ Ramik, R. A.; Organ, R. M.; Mandarino, J. A. (2003). "On Type Romarchite and Hydroromarchite from Boundary Falls, Ontario, and Notes on Other Occurrences". The Canadian Mineralogist. 41 (3): 649–657. Bibcode:2003CaMin..41..649R. doi:10.2113/gscanmin.41.3.649.
^ Walsh, Aron; Watson, Graeme W. (2004). "Electronic structures of rocksalt, litharge, and herzenbergite SnO by density functional theory". Physical Review B. 70 (23): 235114. Bibcode:2004PhRvB..70w5114W. doi:10.1103/PhysRevB.70.235114.
^ Mei, Antonio B.; Miao, Ludi; Wahila, Matthew J.; Khalsa, Guru; Wang, Zhe; Barone, Matthew; Schreiber, Nathaniel J.; Noskin, Lindsey E.; Paik, Hanjong; Tiwald, Thomas E.; Zheng, Qiye (2019-10-21). "Adsorption-controlled growth and properties of epitaxial SnO films". Physical Review Materials. 3 (10): 105202. Bibcode:2019PhRvM...3j5202M. doi:10.1103/PhysRevMaterials.3.105202. S2CID 208008118.
^ Moreno, M. S.; Varela, A.; Otero-Díaz, L. C. (1997). "Cation nonstoichiometry in tin-monoxide-phaseSn1−δOwith tweed microstructure". Physical Review B. 56 (9): 5186–5192. doi:10.1103/PhysRevB.56.5186.
^ Science and Technology of Chemiresistor Gas Sensors By Dinesh K. Aswal, Shiv K. Gupta (2006), Nova Publishers, ISBN 1-60021-514-9
^ "Red Glass Coloration - A Colorimetric and Structural Study" By Torun Bring. Pub. Vaxjo University.
^ Peplinski, D.R.; Wozniak, W.T.; Moser, J.B. (1980). "Spectral Studies of New Luminophors for Dental Porcelain" (PDF). Journal of Dental Research. 59 (9). Jdr.iadrjournals.org: 1501–1506. doi:10.1177/00220345800590090801. PMID 6931128. S2CID 20191368. Retrieved 2012-04-05.^{[permanent dead link]}