Silver(II) fluoride

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Silver(II) fluoride
Silver(II)-fluoride-3D-ionic.png
Names
IUPAC name
silver(II) fluoride
Other names
silver difluoride
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.029.124
EC Number 232-037-5
PubChem CID
Properties
AgF2
Molar mass 145.865 g/mol
Appearance white or grey crystalline powder, hygroscopic
Density 4.58 g/cm3
Melting point 690 °C (1,274 °F; 963 K)
Boiling point 700 °C (1,292 °F; 973 K)(decomposes)
Decomposes violently
Structure
orthorhombic
tetragonally elongated
octahedral coordination
linear
Hazards
Main hazards toxic, reacts violently
with water, powerful oxidizer
Safety data sheet MSDS
NFPA 704
Flammability code 0: Will not burn. E.g., waterHealth code 3: Short exposure could cause serious temporary or residual injury. E.g., chlorine gasReactivity code 3: Capable of detonation or explosive decomposition but requires a strong initiating source, must be heated under confinement before initiation, reacts explosively with water, or will detonate if severely shocked. E.g., fluorineSpecial hazard W+OX: Reacts with water in an unusual or dangerous manner AND is oxidizer.Silver%28II%29 fluoride
0
3
3
W
OX
Related compounds
Other anions
Silver(I,III) oxide
Other cations
Copper(II) fluoride
Palladium(II) fluoride
Zinc fluoride
Cadmium(II) fluoride
Mercury(II) fluoride
Related compounds
Silver subfluoride
Silver(I) fluoride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Silver(II) fluoride is a chemical compound with the formula AgF2. It is a rare example of a silver(II) compound. Silver usually exists in its +1 oxidation state. It is used as a fluorinating agent.

Chemical compound Substance composed of multiple elements

A chemical compound is a chemical substance composed of many identical molecules composed of atoms from more than one element held together by chemical bonds. A chemical element bonded to an identical chemical element is not a chemical compound since only one element, not two different elements, is involved.

A chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, such as parentheses, dashes, brackets, commas and plus (+) and minus (−) signs. These are limited to a single typographic line of symbols, which may include subscripts and superscripts. A chemical formula is not a chemical name, and it contains no words. Although a chemical formula may imply certain simple chemical structures, it is not the same as a full chemical structural formula. Chemical formulas can fully specify the structure of only the simplest of molecules and chemical substances, and are generally more limited in power than are chemical names and structural formulas.

Silver Chemical element with atomic number 47

Silver is a chemical element with symbol Ag and atomic number 47. A soft, white, lustrous transition metal, it exhibits the highest electrical conductivity, thermal conductivity, and reflectivity of any metal. The metal is found in the Earth's crust in the pure, free elemental form, as an alloy with gold and other metals, and in minerals such as argentite and chlorargyrite. Most silver is produced as a byproduct of copper, gold, lead, and zinc refining.

Contents

Preparation

AgF2 can be synthesized by fluorinating Ag2O with elemental fluorine. Also, at 200 °C (473 K) elemental fluorine will react with AgF or AgCl to produce AgF2. [1] [2]

Fluorine Chemical element with atomic number 9

Fluorine is a chemical element with symbol F and atomic number 9. It is the lightest halogen and exists as a highly toxic pale yellow diatomic gas at standard conditions. As the most electronegative element, it is extremely reactive, as it reacts with almost all other elements, except for helium and neon.

Silver(I) fluoride chemical compound

Silver(I) fluoride is the inorganic compound with the formula AgF. It is one of the three main fluorides of silver, the others being silver subfluoride and silver(II) fluoride. AgF has relatively few niche applications; it has been employed as a fluorination and desilylation reagent in organic synthesis and in aqueous solution as a topical caries treatment in dentistry.

As a strong fluorinating agent, AgF2 should be stored in Teflon or a passivated metal container. It is light sensitive.

AgF2 can be purchased from various suppliers, the demand being less than 100 kg/year. While laboratory experiments find use for AgF2, it is too expensive for large scale industry use. In 1993, AgF2 cost between 1000-1400 US dollars per kg.

Composition and structure

AgF2 is a white crystalline powder, but it is usually black/brown due to impurities. The F/Ag ratio for most samples is < 2, typically approaching 1.75 due to contamination with Ag and oxides and carbon. [3]

Oxygen Chemical element with atomic number 8

Oxygen is a chemical element with symbol O and atomic number 8. It is a member of the chalcogen group on the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as well as with other compounds. By mass, oxygen is the third-most abundant element in the universe, after hydrogen and helium. At standard temperature and pressure, two atoms of the element bind to form dioxygen, a colorless and odorless diatomic gas with the formula O
2
. Diatomic oxygen gas constitutes 20.8% of the Earth's atmosphere. As compounds including oxides, the element makes up almost half of the Earth's crust.

Carbon Chemical element with atomic number 6

Carbon is a chemical element with symbol C and atomic number 6. It is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Three isotopes occur naturally, 12C and 13C being stable, while 14C is a radionuclide, decaying with a half-life of about 5,730 years. Carbon is one of the few elements known since antiquity.

For some time, it was doubted silver was actually in the +2 oxidation state rather in some combination of states such as AgI[AgIIIF4], which would be similar to silver(I,III) oxide. Neutron diffraction studies, however, confirmed its description as silver(II). The AgI[AgIIIF4] was found to be present at high temperatures, but it was unstable with respect to AgF2. [4]

Silver(I,III) oxide is the inorganic compound with the formula Ag4O4. It is a component of silver oxide-zinc alkaline batteries. It can be prepared by the slow addition of a silver(I) salt to a persulfate solution e.g. AgNO3 to a Na2S2O8 solution. It adopts an unusual structure, being a mixed-valence compound. It is a dark brown solid that decomposes with evolution of O2 in water. It dissolves in concentrated nitric acid to give brown solutions containing the Ag2+ ion.

Neutron diffraction

Neutron diffraction or elastic neutron scattering is the application of neutron scattering to the determination of the atomic and/or magnetic structure of a material. A sample to be examined is placed in a beam of thermal or cold neutrons to obtain a diffraction pattern that provides information of the structure of the material. The technique is similar to X-ray diffraction but due to their different scattering properties, neutrons and X-rays provide complementary information: X-Rays are suited for superficial analysis, strong x-rays from synchrotron radiation are suited for shallow depths or thin specimens, while neutrons having high penetration depth are suited for bulk samples.

In the gas phase, AgF2 is believed to have D∞h symmetry.

Approximately 14 kcal/mol (59 kJ/mol) separate the ground and first states. The compound is paramagnetic, but it becomes ferromagnetic at temperatures below −110 °C (163 K).

Uses

AgF2 is a strong fluorinating and oxidising agent. It is formed as an intermediate in the catalysis of gaseous reactions with fluorine by silver. With fluoride ions, it forms complex ions such as AgF
3
, the blue-violet AgF2−
4
, and AgF4−
6
. [5]

It is used in the fluorination and preparation of organic perfluorocompounds. [6] This type of reaction can occur in three different ways (here Z refers to any element or group attached to carbon, X is a halogen):

  1. CZ3H + 2 AgF2 → CZ3F +HF + 2 AgF
  2. CZ3X + 2AgF2 → CZ3F +X2 + 2 AgF
  3. Z2C=CZ2 + 2 AgF2 → Z2CFCFZ2 + 2 AgF

Similar transformations can also be effected using other high valence metallic fluorides such as CoF3, MnF3, CeF4, and PbF4.

AgF
2
is also used in the fluorination of aromatic compounds, although selective monofluorinations are more difficult: [7]

C6H6 + 2 AgF2 → C6H5F + 2 AgF + HF

AgF
2
oxidises xenon to xenon difluoride in anhydrous HF solutions. [8]

2 AgF2 + Xe → 2 AgF + XeF2

It also oxidises carbon monoxide to carbonyl fluoride.

2 AgF2 + CO → 2 AgF + COF2

It reacts with water to form oxygen gas:[ citation needed ]

4 AgF2 + 4 H2O → 2 Ag2O + 8 HF + O2

AgF
2
can be used to selectively fluorinate pyridine at the ortho position under mild conditions. [9]

Safety

AgF
2
is a very strong oxidizer that reacts violently with water, [10] reacts with dilute acids to produce ozone, oxidizes iodide to iodine, [10] [11] and upon contact with acetylene forms the contact explosive silver acetylide. [12] It is light-sensitive, [10] very hygroscopic and corrosive. It decomposes violently on contact with hydrogen peroxide, releasing oxygen gas. [12] It also liberates HF, F
2
, and elemental silver. [11]

Related Research Articles

Bromine Chemical element with atomic number 35

Bromine is a chemical element with symbol Br and atomic number 35. It is the third-lightest halogen, and is a fuming red-brown liquid at room temperature that evaporates readily to form a similarly coloured gas. Its properties are thus intermediate between those of chlorine and iodine. Isolated independently by two chemists, Carl Jacob Löwig and Antoine Jérôme Balard, its name was derived from the Ancient Greek βρῶμος ("stench"), referencing its sharp and disagreeable smell.

Noble gas compounds are chemical compounds that include an element from the noble gases, group 18 of the periodic table. Although the noble gases are generally unreactive elements, many such compounds have been observed, particularly involving the element xenon. From the standpoint of chemistry, the noble gases may be divided into two groups: the relatively reactive krypton, xenon (12.1 eV), and radon (10.7 eV) on one side, and the very unreactive argon (15.8 eV), neon (21.6 eV), and helium (24.6 eV) on the other. Consistent with this classification, Kr, Xe, and Rn form compounds that can be isolated in bulk at or near standard temperature and pressure, whereas He, Ne, Ar have been observed to form true chemical bonds using spectroscopic techniques, but only when frozen into a noble gas matrix at temperatures of 40 K or lower, in supersonic jets of noble gas, or under extremely high pressures with metals.

Halogenation is a chemical reaction that involves the addition of one or more halogens to a compound or material. The pathway and stoichiometry of halogenation depends on the structural features and functional groups of the organic substrate, as well as on the specific halogen. Inorganic compounds such as metals also undergo halogenation.

Tungsten(VI) fluoride, also known as tungsten hexafluoride, is an inorganic compound with the formula WF6. It is a toxic, corrosive, colorless gas, with a density of about 13 g/L (roughly 11 times heavier than air.) It is one of the densest known gases under standard conditions. WF6 is commonly used by the semiconductor industry to form tungsten films, through the process of chemical vapor deposition. This layer serves as a low-resistivity metallic "interconnect". It is one of seventeen known binary hexafluorides.

An interhalogen compound is a molecule which contains two or more different halogen atoms and no atoms of elements from any other group.

Oxygen fluoride Wikimedia disambiguation page about all possible oxygen fluorides

Oxygen fluorides are compounds of elements oxygen and fluorine with the general formula OnF2, where n = 1 to 6. Many different oxygen fluorides are known:

Bromine pentafluoride chemical compound

Bromine pentafluoride, BrF5, is an interhalogen compound and a fluoride of bromine. It is a strong fluorination reagent.

Xenon hexafluoride chemical compound

Xenon hexafluoride is a noble gas compound with the formula XeF6 and the highest of the three known binary fluorides of xenon, the other two being XeF2 and XeF4. All known are exergonic and stable at normal temperatures. XeF6 is the strongest fluorinating agent of the series. At room temperature, it is a colorless solid that readily sublimes into intensely yellow vapors.

Cobalt(III) fluoride chemical compound

Cobalt(III) fluoride is the inorganic compound with the formula CoF3. A dihydrate is also known. The anhydrous compound is a hygroscopic brown solid. It is used to synthesize organofluorine compounds.

Hydrogen fluoride chemical compound

Hydrogen fluoride is a chemical compound with the chemical formula HF. This colorless gas or liquid is the principal industrial source of fluorine, often as an aqueous solution called hydrofluoric acid. It is an important feedstock in the preparation of many important compounds including pharmaceuticals and polymers. HF is widely used in the petrochemical industry as a component of superacids. Hydrogen fluoride boils near room temperature, much higher than other hydrogen halides.

Xenon difluoride chemical compound

Xenon difluoride is a powerful fluorinating agent with the chemical formula XeF
2
, and one of the most stable xenon compounds. Like most covalent inorganic fluorides it is moisture-sensitive. It decomposes on contact with light or water vapor but is otherwise stable to storage. Xenon difluoride is a dense, white crystalline solid.

Selenium tetrafluoride chemical compound

Selenium tetrafluoride (SeF4) is an inorganic compound. It is a colourless liquid that reacts readily with water. It can be used as a fluorinating reagent in organic syntheses (fluorination of alcohols, carboxylic acids or carbonyl compounds) and has advantages over sulfur tetrafluoride in that milder conditions can be employed and it is a liquid rather than a gas.

Xenon oxytetrafluoride chemical compound

Xenon oxytetrafluoride (XeOF4) is an inorganic chemical compound. As are most xenon oxides, it is extremely reactive and unstable, and hydrolyses in water to give dangerously hazardous and corrosive products, including hydrogen fluoride:

Krypton difluoride chemical compound

Krypton difluoride, KrF2 is a chemical compound of krypton and fluorine. It was the first compound of krypton discovered. It is a volatile, colourless solid. The structure of the KrF2 molecule is linear, with Kr−F distances of 188.9 pm. It reacts with strong Lewis acids to form salts of the KrF+ and Kr
2
F+
3
cations.

Manganese(IV) fluoride chemical compound

Manganese tetrafluoride, MnF4, is the highest fluoride of manganese. It is a powerful oxidizing agent and is used as a means of purifying elemental fluorine.

Arsenic trifluoride is a chemical compound of arsenic and fluorine with the chemical formula AsF3. It is a colorless liquid which reacts readily with water.

A hexafluoride is a chemical compound with the general formula QXnF6, QXnF6m−, or QXnF6m+. Many molecules fit this formula. An important hexafluoride is hexafluorosilicic acid (H2SiF6), which is a byproduct of the mining of phosphate rock. In the nuclear industry, uranium hexafluoride (UF6) is an important intermediate in the purification of this element.

Chromyl fluoride chemical compound

Chromyl fluoride is an inorganic compound with the formula CrO2F2. It is a violet-red colored crystalline solid that melts to an orange-red liquid.

Vanadium pentafluoride chemical compound

Vanadium(V) fluoride is the inorganic compound with the chemical formula VF5. It is a colorless volatile liquid. It is a highly reactive compound, as indicated by its ability to fluorinate organic substances.

Fluorine forms a great variety of chemical compounds, within which it always adopts an oxidation state of −1. With other atoms, fluorine forms either polar covalent bonds or ionic bonds. Most frequently, covalent bonds involving fluorine atoms are single bonds, although at least two examples of a higher order bond exist. Fluoride may act as a bridging ligand between two metals in some complex molecules. Molecules containing fluorine may also exhibit hydrogen bonding. Fluorine's chemistry includes inorganic compounds formed with hydrogen, metals, nonmetals, and even noble gases; as well as a diverse set of organic compounds. For many elements the highest known oxidation state can be achieved in a fluoride. For some elements this is achieved exclusively in a fluoride, for others exclusively in an oxide; and for still others the highest oxidation states of oxides and fluorides are always equal.

References

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  2. Encyclopedia of Chemical Technology. Kirk-Othermer. Vol.11, 4th Ed. (1991)
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  4. Hans-Christian Miller; Axel Schultz & Magdolna Hargittai (2005). "Structure and Bonding in Silver Halides. A Quantum Chemical Study of the Monomers: Ag2X, AgX, AgX2, and AgX3(X = F, Cl, Br, I)". J. Am. Chem. Soc. 127 (22): 8133–45. doi:10.1021/ja051442j. PMID   15926841.
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  6. Rausch, D.; Davis, r.; Osborne, D. W. (1963). "The Addition of Fluorine to Halogenated Olefins by Means of Metal Fluorides". J. Org. Chem. 28 (2): 494–497. doi:10.1021/jo01037a055.
  7. Zweig, A.; Fischer, R. G.; Lancaster, J. (1980). "New Methods for Selective Monofluorination of Aromatics Using Silver Difluoride". J. Org. Chem. 45 (18): 3597. doi:10.1021/jo01306a011.
  8. Levec, J.; Slivnik, J.; Zemva, B. (1974). "On the Reaction Between Xenon and Fluorine". Journal of Inorganic Nuclear Chemistry. 36 (5): 997. doi:10.1016/0022-1902(74)80203-4.
  9. Fier, P. S.; Hartwig, J. F. (2013). "Selective C-H Fluorination of Pyridines and Diazines Inspired by a Classic Amination Reaction". Science. 342: 956. doi:10.1126/science.1243759. PMID   24264986.
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  12. 1 2 Richard P. Pohanish; Stanley A. Greene (2009). Wiley Guide to Chemical Incompatibilities (3rd ed.). John Wiley and Sons. p. 93. ISBN   0-470-38763-7.