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
CAS Number	7783-53-1 Y
3D model (JSmol)	Interactive image
ChemSpider	74193 Y
ECHA InfoCard	100.029.096
EC Number	232-006-6
PubChem CID	82213
RTECS number	OP0882600
UNII	VHG84D268X Y
CompTox Dashboard (EPA)	DTXSID50893904
InChI InChI=1S/3FH.Mn/h3*1H;/q;;;+3/p-3 Y Key: SRVINXWCFNHIQZ-UHFFFAOYSA-K Y InChI=1/3FH.Mn/h3*1H;/q;;;+3/p-3 Key: SRVINXWCFNHIQZ-DFZHHIFOAX
SMILES [Mn+3].[F-].[F-].[F-]
Properties
Chemical formula	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)
Solubility in water	hydrolysis
Magnetic susceptibility (χ)	+10,500·10−6 cm3/mol
Structure
Crystal structure	Monoclinic, mS48
Space group	C2/c, No. 15
Coordination geometry	distorted octahedral
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	toxic fumes
GHS labelling:[1]
Pictograms
Signal word	Danger
Hazard statements	H272, H301, H312, H315, H319, H332, H335
Precautionary statements	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). N verify (what is YN ?) 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.