Manganese(III) fluoride

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Manganese(III) fluoride
Image:Manganese(III) fluoride.jpg
General
Systematic name Manganese(III) fluoride
Other names Manganese trifluoride
Molecular formula F3Mn
Molar mass 111.938 g/mol
Appearance purple-pink powder
CAS number [7783-53-1]
Properties
Density and phase 3.54 g/cm3, solid
Solubility in water hydrolysis
Other solvents 0.164 g/100 mL in HF
Melting point  ?°C (? K)
Structure
Coordination
geometry
distorted octahedral
Crystal structure VF3
Hazards
MSDS External MSDS
Main hazards toxic fumes
NFPA 704
R/S statement R: 8-20/21/22-36/37/38
S: 17-26-36/37/39
RTECS number OP0882600
Related compounds
Related compounds Manganese acetylacetonate
Cobalt(III) fluoride
Except where noted otherwise, data are given for
materials in their standard state (at 25°C, 100 kPa)
Infobox disclaimer and references

Manganese trifluoride is the chemical compound with the formula MnF3. This purplish solid is highly reactive, being unstable in moist air and liberating F2 upon heating. MnF3 is useful for converting hydrocarbons into fluorocarbons, i.e. it is a fluorination agent.[1]

R3C-H + 2 MnF3 → R3C-F + HF + 2MnF2

A related fluorinating reagent is CoF3.

Contents

[edit] Synthesis and reactions

MnF3 can be prepared by treating a solution of MnF2 in anhydrous hydrogen fluoride with fluorine:[2]

MnF2 + 0.5 F2 → MnF3

In the crystalline state, MnF3 resembles vanadium(III) fluoride: both feature octahedal metal centers with the same average M-F bond distances. In the Mn compound, however, is distorted (and hence a monoclinic unit cell vs a higher symmetry one) due to the Jahn-Teller effect, with pairs of Mn-F distances of 1.79, 1.91, 2.09 A.[3][4][5] Jahn-Teller distortions are characteristic of the presence of four d-electrons in the valence shell.

[edit] Related Mn(III) and Mn(IV) compounds

The fluorination of MnF2 in HF, if conducted in the presence of UV-irradiation, gives MnF4. This tetrafluoride is a relatively rare Mn(IV) species, the most famous example being manganese dioxide.

Other manganese(III) compounds include manganese(III) acetate (CAS #993-02-2) manganese acetylacetonate (CAS# 14284-89-0), Both are employed as oxidants in organic synthesis. MnF3 is Lewis acidic and forms a variety of derivatives. Two examples are K2MnF3(SO4)[6] and K2MnF5.

[edit] Safety considerations

Like other reactive inorganic fluorides, MnF3 should be stored in a polyethylene bottles.

[edit] References

  1. ^ Burley, G. A.; Taylor, R. "Manganese(III) fluoride" in Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette) 2004, J. Wiley & Sons, New York. DOI: 10.1002/047084289.
  2. ^ Z. Mazej (2002). "Room temperature syntheses of MnF3, MnF4 and hexafluoromanganete(IV) salts of alkali cations". Journal of Fluorine Chemistry 114 (1): 75-80. DOI:10.1016/S0022-1139(01)00566-8. 
  3. ^ Wells, A.F. (1984) Structural Inorganic Chemistry, Oxford: Clarendon Press. ISBN 0-19-855370-6.
  4. ^ Hepworth, M. A.; Jack, K. H.; Nyholm, R. S. ”Interatomic Bonding in Manganese Trifluoride” Nature 1957, 179, 211 - 212. doi:10.1038/179211b0
  5. ^ M. A. Hepworth, K. H. Jack (1957). "The crystal structure of manganese trifluoride, MnF3". Acta Crystallographica 10: 345-351. DOI:10.1107/S0365110X57001024. 
  6. ^ Bhattacharjee, M. N; Chaudhuri, M. K. “Dipotassium Trifluorosulfatomanganate(III)” Inorganic Syntheses, 1990, volume 27, pages 312-313. ISBN 0-471-50976-0

[edit] External links