Manganese(III) fluoride

Manganese(III) fluoride (also known as Manganese trifluoride) is the inorganic compound with the formula MnF3. This red/purplish solid is useful for converting hydrocarbons into fluorocarbons, i.e., it is a fluorination agent.[2] It forms a hydrate and many derivatives.

Manganese(III) fluoride
Manganese(III) fluoride
Names
IUPAC name
Manganese(III) fluoride
Other names
Manganese trifluoride, manganic fluoride
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.029.096
EC Number
  • 232-006-6
RTECS number
  • OP0882600
UNII
  • InChI=1S/3FH.Mn/h3*1H;/q;;;+3/p-3 checkY
    Key: SRVINXWCFNHIQZ-UHFFFAOYSA-K checkY
  • InChI=1/3FH.Mn/h3*1H;/q;;;+3/p-3
    Key: SRVINXWCFNHIQZ-DFZHHIFOAX
  • [Mn+3].[F-].[F-].[F-]
Properties
MnF3
Molar mass 111.938 g/mol
Appearance purple-pink powder
hygroscopic
Density 3.54 g/cm3
Melting point > 600 °C (1,112 °F; 873 K) (decomposes)
hydrolysis
+10,500·10−6 cm3/mol
Structure
Monoclinic, mS48
C2/c, No. 15
distorted octahedral
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
 toxic fumes
GHS labelling:[1]
GHS03: OxidizingGHS06: Toxic
Danger
H272, H301, H312, H315, H319, H332, H335
P220, P261, P280, P301+P310, P305+P351+P338
Related compounds
Other anions
 manganese(III) oxide, manganese(III) acetate
Other cations
 chromium(III) fluoride, iron(III) fluoride. cobalt(III) fluoride
Related compounds
 manganese(II) fluoride, manganese(IV) 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

Synthesis, structure and reactions

MnF3 can be prepared by treating a solution of MnF2 in hydrogen fluoride with fluorine:[3]

MnF2 + 0.5 F2 → MnF3

It can also be prepared by the reaction of elemental fluorine with a manganese(II) halide at ~250 °C.[4]

Structure

Like vanadium(III) fluoride, MnF3 features octahedral 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 Å.[5][6][7]

The hydrate MnF3.3H2O is obtained by crystallisation of MnF3 from hydrofluoric acid. The hydrate exists as two polymorphs, with space groups P21/c and P21/a. Each consists of the salt [Mn(H2O)4F2]+[Mn(H2O)2F4]− ).[8]

Reactions

MnF3 is Lewis acidic and forms a variety of derivatives. One example is K2MnF3(SO4).[9] MnF3 reacts with sodium fluoride to give the octahedral hexafluoride:[4]

3NaF + MnF3 → Na3MnF6

Related reactions salts of the anions MnF52− or MnF4−. These anions adopt chain and layer structures respectively, with bridging fluoride. Manganese remains 6 coordinate, octahedral, and trivalent in all of these materials.[4]

Manganese(III) fluoride fluorinates organic compounds including aromatic hydrocarbons,[10] cyclobutenes,[11] and fullerenes.[12]

On heating, MnF3 decomposes to manganese(II) fluoride.[13][14]

MnF3 is a source of MnCl3 complexes by reaction with bismuth trichloride.[15]

See also
  • CoF3, another fluorinating agent based on a transition metal in an oxidising +3 state.

References
  1. GHS: sigma-aldrich 339296
  2. Burley, G. A.; Taylor, R. (2004). "Manganese(III) Fluoride". Encyclopedia of Reagents for Organic Synthesis. J. Wiley & Sons. doi:10.1002/047084289X.rn00411.
  3. 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.
  4. Inorganic chemistry, Catherine E. Housecroft, A.G. Sharpe, pp.711-712, section Manganese (III) , googlebooks link
  5. Wells, A.F. (1984) Structural Inorganic Chemistry, Oxford: Clarendon Press. ISBN 0-19-855370-6.
  6. Hepworth, M. A.; Jack, K. H.; Nyholm, R. S. (1957). "Interatomic Bonding in Manganese Trifluoride". Nature. 179 (4552): 211–212. Bibcode:1957Natur.179..211H. doi:10.1038/179211b0. S2CID 4208409.
  7. M. A. Hepworth; K. H. Jack (1957). "The Crystal Structure of Manganese Trifluoride, MnF3". Acta Crystallographica. 10 (5): 345–351. doi:10.1107/S0365110X57001024.
  8. Molinier Michel; Massa Werner (1992). "Structures of two polymorphs of MnF3·3H2O". Journal of Fluorine Chemistry. 57 (1–3): 139–146. doi:10.1016/S0022-1139(00)82825-0.
  9. Bhattacharjee, M. N; Chaudhuri, M. K. (2007). "Dipotassium Trifluorosulfato‐Manganate(III)". Inorganic Syntheses. pp. 312–313. doi:10.1002/9780470132586.ch61. ISBN 978-0-470-13258-6. {{cite book}}: |journal= ignored (help)
  10. Fluorination of p-chlorobenzotrifluoride by manganese trifluoride Archived 2011-08-23 at the Wayback Machine A. Kachanov, V. Kornilov, V.Belogay , Fluorine Notes :Vol. 1 (1) November–December 1998 , via notes.fluorine1.ru
  11. Junji Mizukado; Yasuhisa Matsukawa; Heng-dao Quan; Masanori Tamura; Akira Sekiya (2006). "Fluorination of Fluoro-Cyclobutene with High-Valency Metal Fluoride". Journal of Fluorine Chemistry. 127: 79–84. doi:10.1016/j.jfluchem.2005.10.007.
  12. V. É. Aleshina; A. Ya. Borshchevskii; E. V. Skokan; I. V. Arkhangel'skii; A.V. Astakhov; N.B. Shustova (2002). "Fluorination of the Cubic and Hexagonal C60 Modifications by Crystalline Manganese Trifluoride". Physics of the Solid State. 44 (4): 629–630. Bibcode:2002PhSS...44..629A. doi:10.1134/1.1470543. S2CID 94250136.
  13. Chisholm, Hugh, ed. (1911). "Manganese § Manganic Salts" . Encyclopædia Britannica. Vol. 17 (11th ed.). Cambridge University Press. p. 570.
  14. In situ time-resolved X-ray diffraction study of manganese trifluoride thermal decomposition , J.V. Raua, V. Rossi Albertinib, N.S. Chilingarova, S. Colonnab, U. Anselmi Tamburini, Journal of Fluorine Chemistry 4506 (2001) 1–4 , online version
  15. Nachtigall, Olaf; Pataki, Astrid; Molski, Matthias; Lentz, Dieter; Spandl, Johann (2015). "Solvates of Manganese Trichloride Revisited - Synthesis, Isolation, and Crystal Structure of MnCl3(THF)3". Zeitschrift für Anorganische und Allgemeine Chemie. 641 (6): 1164–1168. doi:10.1002/zaac.201500106.

Further reading
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