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! | Silver(ii) Fluoride |- | align="center" colspan="2" bgcolor="#ffffff" | Silver(II) Fluoride Structure |- ! | General |- | Systematic Name | silver(II) fluoride |- | Other names | silver difluoride |- | Molecular Formula | AgF2 |- | Molar Mass | 145.865 g/mol |- | Appearance | white or grey crystaline powder, Hygroscopic |- | CAS Number | 7775-41-9 |- ! | Properties |- | Density and Phase | 4.58 g/cm3 |- | Solubility in Water | Decomposes, violently |- | Melting Point | 690 °C (963 K) |- | Boiling Point | decomposes at 700°C (973K) |- ! | Structure |- | Molecular Shape | linear |- | Coordination geometry | tetragonally elongated octahedral coordination |- | Crystal Structure | orthorombic |- ! | Hazards |- | MSDS | MSDS |- | Main Hazard s | toxic, reacts violently with water, powerful oxidizer |- ! | Related compounds |- | Other Ag(II) Halide s | no other AgX2 stable at room temp. |- | Related compounds | Silver(I) Fluoride (AgF), Ag2F, AgO, Ag2O |- | | Except where noted otherwise, data are given for materials in their |- |} Silver(II) fluoride has the formula AgF2. It is currently the only silver (II) compound that is known to be stable at room temperature (25 °C). Silver is usually present in its +1 Oxidation State , making the formation of AgF2 unusual. 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. Silver(II) fluoride should be stored in Teflon , a passivated metal container, or a Quartz tube. AgF2 is light sensitive. AgF2 can be purchased from various suppliers, the demand being less than 100kg/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 Dollar per kg. Composition and structure Pure AgF2 is a white crystalline powder, but it is usually black/brown-colored due to contaminates. The F/Ag ratio for most samples is < 2, typically approaching 1.75 due to contamination with Ag and Oxides and Carbon . For some time, it was doubted silver was actually in the 2+ oxidation state rather in some combination of states such as Ag(I) which would be similar to Silver Oxide . However, Neutron Diffraction studies confirm the description as silver(II). The Ag(I)[Ag(III)F4 was found to be present at high temperatures, but it was unstable with respect to AgF2. AgF2 is believed to have D∞h Symmetry . Approximately 14 Kcal / Mol separate the Ground and first State s. The compound is Paramagnetic , but it becomes Ferromagnetic at temperatures below -110 °C (163 K). Uses AgF2 is a strong fluorinating and oxidation agent. Illustrative applications are listed below.
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.
Substitutive Fluorination s of Aromatic compounds are readily achieved, but selective monofluorinations are more difficult. :C6H6 + 2 AgF2 → C6H5F + 2 AgF + HF
References #Note|encyclo}} ''Encyclopedia of Chemical Technology.'' Kirk-Othermer. Vol.11, 4th Ed. (1991) #Note|XPS}} J.T. Wolan, G.B. Hoflund. "Surface Characterization Study of AgF and AgF2 Powders Using XPS and ISS," ''Applied Surface Science.'' 125, (1998). #Note|structure}} Hans-Christian Miller, Axel Schultz, and Magdolna Hargittai. "Structure and Bonding in Silver Halides: A Quantum...X=F, Cl, Br, I," J. Am. Chem. Soc. 127(22), (2005). # Note|rxns}} Douglas Rausch, Ralph Davis, and D. Wendell Osborne. "The Addition of Fluorine to Halogenated Olefins by Means of Metal Fluorides," J. Org. Chem. 28, pp. 494-497, Jul. (1962). #Note|monof}} Arnold Zweig, Robert G. Fischer, and John Lancaster. "New Methods for Selective Monofluorination of Aromatics Using Silver Difluoride," J. Org. Chem. 45, (1980). # Note|Xenon}} J. Levec, J. Slivnik, and B. Zemva. "On the Reaction Between Xenon and Fluorine," ''J. Inorg. Nucl. Chem.'' Vol. 36, (1974). External links
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