tin(II) fluoride

{{Use British English|date=June 2019}}

{{chembox

| Verifiedfields = changed

| Watchedfields = changed

| verifiedrevid = 441026513

| IUPACName = Tin(II) fluoride

| ImageCaption = {{Color box|#C0C0C0|border=darkgray}} Sn2+; {{Color box|#99CC00|border=darkgray}} F

| OtherNames = Stannous fluoride

| ImageFile = Kristallstruktur Zinn(II)-fluorid.png

|Section1={{Chembox Identifiers

| CASNo = 7783-47-3

| CASNo_Ref = {{cascite|correct|CAS}}

| UNII_Ref = {{fdacite|correct|FDA}}

| UNII = 3FTR44B32Q

| RTECS = XQ3450000

| UNNumber = 3288

| PubChem = 24550

| InChI = 1S/2FH.Sn/h2*1H;/q;;+2/p-2

| SMILES = F[Sn]F

}}

|Section2={{Chembox Properties

| Formula = SnF2

| MolarMass = 156.69 g/mol

| Appearance = colorless solid

| Density = 4.57 g/cm3

| Solubility = 31 g/100 mL (0 °C);
35 g/100 mL (20 °C);
78.5 g/100 mL (106 °C)

| SolubleOther = soluble in KOH, KF;
negligible in ethanol, ether, chloroform

| MeltingPtC = 213

| BoilingPtC = 850

}}

|Section3={{Chembox Structure

| CrystalStruct = Monoclinic, mS48

| SpaceGroup = C2/c, No. 15

}}

|Section7={{Chembox Hazards

| ExternalSDS = [http://www.inchem.org/documents/icsc/icsc/eics0860.htm ICSC 0860]

| HPhrases =

| PPhrases =

| GHS_ref =

| NFPA-H = 2

| NFPA-F = 0

| NFPA-R = 0

| NFPA-S =

| FlashPt = Non-flammable

}}

|Section6={{Chembox Pharmacology

| ATCCode_prefix = A01

| ATCCode_suffix = AA04

}}

|Section8={{Chembox Related

| OtherAnions = Tin(II) chloride,
Tin(II) bromide,
Tin(II) iodide

| OtherCations = Difluorocarbene,
Carbon tetrafluoride,
Difluorosilylene,
Silicon tetrafluoride,
Difluorogermylene,
Germanium tetrafluoride,
Tin tetrafluoride,
Lead(II) fluoride,
Lead(IV) fluoride

}}

}}

Tin(II) fluoride, commonly referred to commercially as stannous fluoride{{cite press release|title=National Inventors Hall of Fame Announces 2019 Inductees at CES|url=https://www.prnewswire.com/news-releases/national-inventors-hall-of-fame-announces-2019-inductees-at-ces-300774807.html|access-date=6 February 2019|publisher=National Inventors Hall of Fame}}{{cite web|title=Latin Names Variable Charge Metals|url=http://nobel.scas.bcit.ca/chem0010/unit6/6.1.3_binaryvarcharge.htm|work=Nobel.SCAS.BCIT.ca/|publisher=British Columbia Institute of Technology Chemistry Department|access-date=16 June 2013|archive-date=22 July 2020|archive-url=https://web.archive.org/web/20200722102958/http://nobel.scas.bcit.ca/chem0010/unit6/6.1.3_binaryvarcharge.htm|url-status=dead}} (from Latin {{lang|la|stannum}}, 'tin'), is a chemical compound with the formula SnF2. It is a colourless solid used as an ingredient in toothpastes.

Oral health benefits

Stannous fluoride is an alternative to sodium fluoride for the prevention of cavities (tooth decay). It was first released commercially in 1956, in Crest toothpaste. It was discovered and developed by Joseph Muhler and William Nebergall. In recognition of their innovation, they were inducted into the Inventor's Hall of Fame.

The fluoride in stannous fluoride helps to convert the calcium mineral hydroxyapatite in teeth into fluorapatite, which makes tooth enamel more resistant to bacteria-generated acid attacks.{{Cite journal|last1=Groeneveld|first1=A.|last2=Purdell-Lewis|first2=D. J.|last3=Arends|first3=J.|date=1976|title=Remineralization of artificial caries lesions by stannous fluoride|journal=Caries Research|volume=10|issue=3|pages=189–200|issn=0008-6568|pmid=1063601|doi=10.1159/000260201}} The calcium present in plaque and saliva reacts with fluoride to form calcium fluoride on the tooth surface; over time, this calcium fluoride dissolves to allow calcium and fluoride ions to interact with the tooth and form fluoride-containing apatite within the tooth structure.{{Cite journal|last1=Lussi|first1=Adrian|last2=Hellwig|first2=Elmar|last3=Klimek|first3=Joachim|date=2012|title=Fluorides - mode of action and recommendations for use|url=https://pubmed.ncbi.nlm.nih.gov/23192605|journal=Schweizer Monatsschrift für Zahnmedizin = Revue Mensuelle Suisse d'Odonto-Stomatologie = Rivista Mensile Svizzera di Odontologia e Stomatologia|volume=122|issue=11|pages=1030–1042|issn=0256-2855|pmid=23192605}} This chemical reaction inhibits demineralisation and can promote remineralisation of tooth decay. The resulting fluoride-containing apatite is more insoluble, and more resistant to acid and tooth decay.

In addition to fluoride, the stannous ion has benefits for oral health when incorporated in a toothpaste. At similar fluoride concentrations, toothpastes containing stannous fluoride have been shown to be more effective than toothpastes containing sodium fluoride for reducing the incidence of dental caries and dental erosion,{{Cite journal|last1=West|first1=N. X.|last2=He|first2=T.|last3=Macdonald|first3=E. L.|last4=Seong|first4=J.|last5=Hellin|first5=N.|last6=Barker|first6=M. L.|last7=Eversole|first7=S. L.|date=March 2017|title=Erosion protection benefits of stabilized SnF2 dentifrice versus an arginine–sodium monofluorophosphate dentifrice: results from in vitro and in situ clinical studies|journal=Clinical Oral Investigations|language=en|volume=21|issue=2|pages=533–540|doi=10.1007/s00784-016-1905-1|issn=1432-6981|pmc=5318474|pmid=27477786}}{{Cite journal|last1=Ganss|first1=C.|last2=Lussi|first2=A.|last3=Grunau|first3=O.|last4=Klimek|first4=J.|last5=Schlueter|first5=N.|date=2011|title=Conventional and Anti-Erosion Fluoride Toothpastes: Effect on Enamel Erosion and Erosion-Abrasion|url=https://www.karger.com/Article/FullText/334318|journal=Caries Research|language=en|volume=45|issue=6|pages=581–589|doi=10.1159/000334318|pmid=22156703|s2cid=45156274|issn=0008-6568}}{{Cite journal|last1=West|first1=Nicola X.|last2=He|first2=Tao|last3=Hellin|first3=Nikki|last4=Claydon|first4=Nicholas|last5=Seong|first5=Joon|last6=Macdonald|first6=Emma|last7=Farrell|first7=Svetlana|last8=Eusebio|first8=Rachelle|last9=Wilberg|first9=Aneta|date=August 2019|title=Randomized in situ clinical trial evaluating erosion protection efficacy of a 0.454% stannous fluoride dentifrice|journal=International Journal of Dental Hygiene|language=en|volume=17|issue=3|pages=261–267|doi=10.1111/idh.12379|issn=1601-5029|pmc=6850309|pmid=30556372}}{{Cite journal|date=2020-02-12|title=Efficacy of a Stannous-containing Dentifrice for Protecting Against Combined Erosive and Abrasive Tooth Wear In Situ|url=|journal=Oral Health and Preventive Dentistry|volume=18|issue=1|pages=619–624|doi=10.3290/j.ohpd.a44926|pmid=32700515|last1=Zhao|first1=X.|last2=He|first2=T.|last3=He|first3=Y.|last4=Chen|first4=H.}}{{Cite journal|last1=Stookey|first1=G.K.|last2=Mau|first2=M.S.|last3=Isaacs|first3=R.L.|last4=Gonzalez-Gierbolini|first4=C.|last5=Bartizek|first5=R.D.|last6=Biesbrock|first6=A.R.|date=2004|title=The Relative Anticaries Effectiveness of Three Fluoride-Containing Dentifrices in Puerto Rico|url=https://www.karger.com/Article/FullText/80584|journal=Caries Research|language=en|volume=38|issue=6|pages=542–550|doi=10.1159/000080584|pmid=15528909|s2cid=489634|issn=0008-6568|doi-access=free}} as well as reducing gingivitis.{{Cite journal|last1=Parkinson|first1=C. R.|last2=Milleman|first2=K. R.|last3=Milleman|first3=J. L.|date=2020-03-26|title=Gingivitis efficacy of a 0.454% w/w stannous fluoride dentifrice: a 24-week randomized controlled trial|journal=BMC Oral Health|volume=20|issue=1|pages=89|doi=10.1186/s12903-020-01079-6|issn=1472-6831|pmc=7098169|pmid=32216778 |doi-access=free }}{{Cite journal|last1=Hu|first1=Deyu|last2=Li|first2=Xue|last3=Liu|first3=Hongchun|last4=Mateo|first4=Luis R.|last5=Sabharwal|first5=Amarpreet|last6=Xu|first6=Guofeng|last7=Szewczyk|first7=Gregory|last8=Ryan|first8=Maria|last9=Zhang|first9=Yun-Po|date=April 2019|title=Evaluation of a stabilized stannous fluoride dentifrice on dental plaque and gingivitis in a randomized controlled trial with 6-month follow-up|url=|journal=The Journal of the American Dental Association|volume=150|issue=4|pages=S32–S37|doi=10.1016/j.adaj.2019.01.005|pmid=30797257|s2cid=73488958|issn=0002-8177}}{{Cite journal|last1=Mankodi|first1=Suru|last2=Bartizek|first2=Robert D.|last3=Winston|first3=J. Leslie|last4=Biesbrock|first4=Aaron R.|last5=McClanahan|first5=Stephen F.|last6=He|first6=Tao|date=2005|title=Anti-gingivitis efficacy of a stabilized 0.454% stannous fluoride/sodium hexametaphosphate dentifrice|journal=Journal of Clinical Periodontology|language=en|volume=32|issue=1|pages=75–80|doi=10.1111/j.1600-051X.2004.00639.x|pmid=15642062|issn=1600-051X|doi-access=free}}{{Cite journal|last1=Archila|first1=Luis|last2=Bartizek|first2=Robert D.|last3=Winston|first3=J. Leslie|last4=Biesbrock|first4=Aaron R.|last5=McClanahan|first5=Stephen F.|last6=He|first6=Tao|date=2004|title=The Comparative Efficacy of Stabilized Stannous Fluoride/Sodium Hexametaphosphate Dentifrice and Sodium Fluoride/Triclosan/Copolymer Dentifrice for the Control of Gingivitis: A 6-Month Randomized Clinical Study|url=|journal=Journal of Periodontology|language=en|volume=75|issue=12|pages=1592–1599|doi=10.1902/jop.2004.75.12.1592|pmid=15732859|issn=1943-3670}}{{Cite journal|last1=Clark-Perry|first1=Danielle|last2=Levin|first2=Liran|date=December 2020|title=Comparison of new formulas of stannous fluoride toothpastes with other commercially available fluoridated toothpastes: A systematic review and meta-analysis of randomised controlled trials|journal=International Dental Journal|language=en|volume=70|issue=6|pages=418–426|doi=10.1111/idj.12588|pmid=32621315|pmc=9379195 |s2cid=220336087}} Some stannous fluoride-containing toothpastes also contain ingredients that allow for better stain removal.{{Cite journal|last1=He|first1=Tao|last2=Baker|first2=Robert|last3=Bartizek|first3=Robert D.|last4=Biesbrock|first4=Aaron R.|last5=Chaves|first5=Eros|last6=Terézhalmy|first6=Geza|date=2007|title=Extrinsic stain removal efficacy of a stannous fluoride dentifrice with sodium hexametaphosphate|url=https://pubmed.ncbi.nlm.nih.gov/17410949|journal=The Journal of Clinical Dentistry|volume=18|issue=1|pages=7–11|issn=0895-8831|pmid=17410949}}{{Cite journal|last1=Johannsen|first1=A.|last2=Emilson|first2=C.-G.|last3=Johannsen|first3=G.|last4=Konradsson|first4=K.|last5=Lingström|first5=P.|last6=Ramberg|first6=P.|date=December 2019|title=Effects of stabilized stannous fluoride dentifrice on dental calculus, dental plaque, gingivitis, halitosis and stain: A systematic review|url=|journal=Heliyon|volume=5|issue=12|pages=e02850|doi=10.1016/j.heliyon.2019.e02850|doi-access=free |issn=2405-8440|pmc=6909063|pmid=31872105|bibcode=2019Heliy...502850J }} Stabilised stannous fluoride formulations allow for greater bioavailability of the stannous and fluoride ion, increasing their oral health benefits.{{Cite journal|last=White|first=D. J.|date=1995|title=A "return" to stannous fluoride dentifrices|url=https://pubmed.ncbi.nlm.nih.gov/8593190|journal=The Journal of Clinical Dentistry|volume=6|pages=29–36|issn=0895-8831|pmid=8593190}}{{Cite journal|last=Tinanoff|first=N.|date=1995|title=Progress regarding the use of stannous fluoride in clinical dentistry|url=https://pubmed.ncbi.nlm.nih.gov/8593191|journal=The Journal of Clinical Dentistry|volume=6|pages=37–40|issn=0895-8831|pmid=8593191}} A systematic review revealed stabilised stannous fluoride-containing toothpastes had a positive effect on the reduction of plaque, gingivitis and staining, with a significant reduction in calculus and halitosis (bad breath) compared to other toothpastes. A specific formulation of stabilised stannous fluoride toothpastes has shown superior protection against dental erosion and dentine hypersensitivity compared to other fluoride-containing and fluoride-free toothpastes.{{Cite journal|last1=West|first1=Nicola X.|last2=He|first2=Tao|last3=Zou|first3=Yuanshu|last4=DiGennaro|first4=Joe|last5=Biesbrock|first5=Aaron|last6=Davies|first6=Maria|date=February 2021|title=Bioavailable gluconate chelated stannous fluoride toothpaste meta-analyses: Effects on dentine hypersensitivity and enamel erosion|journal=Journal of Dentistry|volume=105|pages=103566|doi=10.1016/j.jdent.2020.103566|issn=1879-176X|pmid=33383100|s2cid=229940161|doi-access=free|hdl=1983/34d78138-703d-484f-864f-ece3d3610d64|hdl-access=free}}

Stannous fluoride was once used under the trade name Fluoristan in the original formulation of the toothpaste brand Crest, though it was later replaced with sodium monofluorophosphate under the trade name Fluoristat. Stabilised stannous fluoride is now the active ingredient in Crest/Oral B Pro-Health brand toothpaste. Although concerns have been previously raised that stannous fluoride may cause tooth staining, this can be avoided by proper brushing and by using a stabilised stannous fluoride toothpaste. Any stannous fluoride staining that occurs due to improper brushing is not permanent, and Crest/Oral B Pro-Health states that its particular formulation is resistant to staining.

Production

SnF2 can be prepared by evaporating a solution of SnO in 40% HF.{{Greenwood&Earnshaw}}

:SnO + 2 HF → SnF2 + H2O

Aqueous solutions

Readily soluble in water, SnF2 is hydrolysed. At low concentration, it forms species such as SnOH+, Sn(OH)2 and Sn(OH)3. At higher concentrations, predominantly polynuclear species are formed, including Sn2(OH)22+ and Sn3(OH)42+.{{cite journal

| title = A critical review of thermodynamic data for inorganic tin species

| journal = Geochimica et Cosmochimica Acta

| year = 2001

| volume = 65

| issue = 18

| pages = 3041–3053

| doi = 10.1016/S0016-7037(01)00645-7

| bibcode=2001GeCoA..65.3041S

| last1 = Séby

| first1 = F.

| last2 = Potin-Gautier

| first2 = M.

| last3 = Giffaut

| first3 = E.

| last4 = Donard

| first4 = O.F.X.

}} Aqueous solutions readily oxidise to form insoluble precipitates of SnIV, which are ineffective as a dental prophylactic.David B. Troy, 2005, Remington: The Science and Practice of Pharmacy, Lippincott Williams & Wilkins, {{ISBN|0-7817-4673-6}}, {{ISBN|978-0-7817-4673-1}} Studies of the oxidation using Mössbauer spectroscopy on frozen samples suggests that O2 is the oxidizing species.{{cite journal

| title = Oxidation of SnF2 stannous fluoride in aqueous solutions

| journal = Hyperfine Interactions

| year = 1994

| volume = 90

| issue = 1

| pages = 435–439

| doi = 10.1007/BF02069152

| bibcode = 1994HyInt..90..435D

| last1 = Denes

| first1 = Georges

| last2 = Lazanas

| first2 = George

| s2cid = 96184099

}}

Lewis acidity

SnF2 acts as a Lewis acid. For example, it forms a 1:1 complex (CH3)3NSnF2 and 2:1 complex [(CH3)3N]2SnF2 with trimethylamine,{{cite journal

| title = Synthesis and studies of trimethylamine adducts with tin(II) halides

| name-list-style=amp | journal = Inorg. Chem.

| year = 1977

| volume = 16

| issue = 1

| pages = 2529–2534

| doi = 10.1021/ic50176a022

| last1=Hsu | first1=C. C. | last2=Geanangel | first2=R. A. }} and a 1:1 complex with dimethylsulfoxide, (CH3)2SO·SnF2.{{cite journal

| title = Donor and acceptor behavior of divalent tin compounds

| name-list-style=amp | journal = Inorg. Chem.

| year = 1980

| volume = 19

| issue = 1

| pages = 110–119

| doi = 10.1021/ic50203a024

| last1=Hsu | first1=Chung Chun | last2=Geanangel | first2=R. A. }}
In solutions containing the fluoride ion, F, it forms the fluoride complexes SnF3, Sn2F5, and SnF2(OH2).Egon Wiberg, Arnold Frederick Holleman (2001) Inorganic Chemistry, Elsevier {{ISBN|0-12-352651-5}}. Crystallization from an aqueous solution containing NaF produces compounds containing polynuclear anions, e.g. NaSn2F5 or Na4Sn3F10 depending on the reaction conditions, rather than NaSnF3. The compound NaSnF3, containing the pyramidal SnF3 anion, can be produced from a pyridine–water solution.{{cite journal

| title = Synthesis and crystal structure of two tin fluoride materials: NaSnF3 (BING-12) and Sn3F3PO4

| journal = Journal of Solid State Chemistry

| year = 2004

| volume = 177

| issue = 3

| pages = 800–805

| doi = 10.1016/j.jssc.2003.09.013

| bibcode = 2004JSSCh.177..800S

| last1 = Salami

| first1 = Tolulope O.

| last2 = Zavalij

| first2 = Peter Y.

| last3 = Oliver

| first3 = Scott R.J

}} Other compounds containing the pyramidal SnF3 anion are known, such as {{chem2|Ca(SnF3)2}}.{{cite journal

| title =Synthesis and Crystal Structure of Calcium Trifluorostannate(II)

|author1=Kokunov Y. V. |author2=Detkov D. G. |author3=Gorbunova Yu. E. |author4=Ershova M. M. |author5=Mikhailov Yu. N. | journal = Doklady Chemistry

| year = 2001

| volume = 376

| issue = 4–6

| pages = 52–54

| doi = 10.1023/A:1018855109716

|s2cid=91430538 }}

Reducing properties

SnF2 is a reducing agent, with a standard reduction potential of Eo (SnIV/ SnII) = +0.15 V.{{Housecroft2nd}} Solutions in HF are readily oxidised by a range of oxidizing agents (O2, SO2 or F2) to form the mixed-valence compound Sn3F8 (containing SnII and SnIV and no Sn–Sn bonds).

Structure

The monoclinic form contains tetramers, Sn4F8, where there are two distinct coordination environments for the Sn atoms. In each case, there are three nearest neighbours, with Sn at the apex of a trigonal pyramid, and the lone pair of electrons sterically active.Wells A.F. (1984) Structural Inorganic Chemistry 5th edition Oxford Science Publications {{ISBN|0-19-855370-6}} Other forms reported have the GeF2 and paratellurite structures.

Molecular SnF<sub>2</sub>

In the vapour phase, SnF2 forms monomers, dimers, and trimers. Monomeric SnF2 is a non-linear with an Sn−F bond length of 206 pm. Complexes of SnF2, sometimes called difluorostannylene, with an alkyne and aromatic compounds deposited in an argon matrix at 12 K have been reported.{{cite journal

| title = Matrix IR spectra and quantum chemical studies of the reaction between difluorostannylene and hept-1-yne. The first direct observation of a carbene analog π-complex with alkyne

| first1 = SE

| last1 = Bogdanov

| first2 = VI

| last2 = Faustov

| first3 = MP

| last3 = Egorov

| first4 = OM

| last4 = Nefedov

| journal = Russian Chemical Bulletin

| year = 1994

| volume = 43

| issue = 1

| pages = 47–49

| doi = 10.1007/BF00699133

| s2cid = 97064510

}}{{cite journal

| title = Study of complexation between difluorostannylene and aromatics by matrix IR spectroscopy

| author = S. E. Boganov, M. P. Egorov and O. M. Nefedov

| journal = Russian Chemical Bulletin

| year = 1999

| volume = 48

| issue = 1

| pages = 98–103

| doi = 10.1007/BF02494408

| s2cid = 94004320

}}

Safety

Stannous fluoride can cause redness and irritation if it is inhaled or comes into contact with the eyes. If ingested, it can cause abdominal pains and shock.{{cite web|url=https://www.ilo.org/dyn/icsc/showcard.display?p_lang=en&p_card_id=0860&p_version=2|title=Stannous fluoride (International Chemical Safety Cards: 0860)|publisher=International Labour Organization|access-date=June 21, 2021}} Rare but serious allergic reactions are possible; symptoms include itching, swelling, and difficulty breathing. Certain formulations of stannous fluoride in dental products may cause mild tooth discoloration; this is not permanent and can be removed by brushing, or can be prevented by using a stabilised stannous fluoride toothpaste.{{cite web|url=http://www.webmd.com/drugs/mono-7156-STANNOUS+FLUORIDE+GEL+-+DENTAL.aspx?drugid=75277&drugname=stannous+fluoride+dent|title=Stannous Fluoride-Dental|publisher=WebMD|access-date=March 11, 2014}}

{{clear}}

References

{{reflist|30em}}

{{Tin compounds}}

{{Stomatological preparations}}

{{fluorine compounds}}

{{DEFAULTSORT:Tin(Ii) Fluoride}}

Category:Fluorides

Category:Metal halides

Category:Tin(II) compounds

Category:Reducing agents