Manganese(IV) fluoride
Encyclopedia
Manganese fluoride (also known as Manganese trifluoride) is the inorganic compound
with the formula MnF3. This red/purplish solid is useful for converting hydrocarbon
s into fluorocarbon
s, i.e., it is a fluorination agent. It also forms a hydrate.
with fluorine
:
It can also be prepared by the reaction of elemental fluorine with a manganese(II) halide at ~250 °C.
: 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 Å.
The hydrate MnF3.3H2O is obtained by crystallisation of MnF3 from hydrofluoric acid. The hydrate is unusual in that it forms two different structures (both based on [Mn(H2O)4F2]+ [Mn(H2O)2F4]- ), which have space group
s P21/c and P21/a.
to give the octahedral hexafluorate anion::
Other reaction conditions give compounds with anion formula MnF52- or MnF4-. These anions are chain and layer structures respectively, with bridging fluorine. Manganese remains 6 coordinate, octahedral, and trivalent in all these materials.
Manganese(III) fluoride fluorinates organic compounds including aromatic hydrocarbons, cyclobutenes, and fullerenes.
On heating, MnF3 decomposes to manganese(II) fluoride
.
. MnF3 is Lewis acidic and forms a variety of derivatives. Two examples are K2MnF3(SO4) and K2MnF5.
on hydrolysis.
, another fluorinating agent based on a transition metal in an oxidising +3 state.
Inorganic compound
Inorganic compounds have traditionally been considered to be of inanimate, non-biological origin. In contrast, organic compounds have an explicit biological origin. However, over the past century, the classification of inorganic vs organic compounds has become less important to scientists,...
with the formula MnF3. This red/purplish solid is useful for converting hydrocarbon
Hydrocarbon
In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons from which one hydrogen atom has been removed are functional groups, called hydrocarbyls....
s into fluorocarbon
Fluorocarbon
Fluorocarbons, sometimes referred to as perfluorocarbons or PFCs, are organofluorine compounds that contain only carbon and fluorine bonded together in strong carbon–fluorine bonds. Fluoroalkanes that contain only single bonds are more chemically and thermally stable than alkanes...
s, i.e., it is a fluorination agent. It also forms a hydrate.
Synthesis
MnF3 can be prepared by treating a solution of MnF2 in hydrogen fluorideHydrogen fluoride
Hydrogen fluoride is a chemical compound with the formula HF. This colorless gas is the principal industrial source of fluorine, often in the aqueous form as hydrofluoric acid, and thus is the precursor to many important compounds including pharmaceuticals and polymers . HF is widely used in the...
with fluorine
Fluorine
Fluorine is the chemical element with atomic number 9, represented by the symbol F. It is the lightest element of the halogen column of the periodic table and has a single stable isotope, fluorine-19. At standard pressure and temperature, fluorine is a pale yellow gas composed of diatomic...
:
- MnF2 + 0.5 F2 → MnF3
It can also be prepared by the reaction of elemental fluorine with a manganese(II) halide at ~250 °C.
Structure
In the crystalline state, MnF3 resembles vanadium(III) fluorideVanadium(III) fluoride
Vanadium fluoride is the chemical compound with the formula VF3. This gray-green, refractory solid is obtained in a two-step procedure from V2O3...
: 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
Jahn-Teller effect
The Jahn–Teller effect, sometimes also known as Jahn–Teller distortion, or the Jahn–Teller theorem, describes the geometrical distortion of non-linear molecules under certain situations. This electronic effect is named after Hermann Arthur Jahn and Edward Teller, who proved, using group theory,...
, with pairs of Mn-F distances of 1.79, 1.91, 2.09 Å.
The hydrate MnF3.3H2O is obtained by crystallisation of MnF3 from hydrofluoric acid. The hydrate is unusual in that it forms two different structures (both based on [Mn(H2O)4F2]+ [Mn(H2O)2F4]- ), which have space group
Space group
In mathematics and geometry, a space group is a symmetry group, usually for three dimensions, that divides space into discrete repeatable domains.In three dimensions, there are 219 unique types, or counted as 230 if chiral copies are considered distinct...
s P21/c and P21/a.
Reactions
MnF3 reacts with sodium fluorideSodium fluoride
Sodium fluoride is an inorganic chemical compound with the formula NaF. A colorless solid, it is a source of the fluoride ion in diverse applications. Sodium fluoride is less expensive and less hygroscopic than the related salt potassium fluoride....
to give the octahedral hexafluorate anion::
- 3NaF + MnF3 → Na3MnF6
Other reaction conditions give compounds with anion formula MnF52- or MnF4-. These anions are chain and layer structures respectively, with bridging fluorine. Manganese remains 6 coordinate, octahedral, and trivalent in all these materials.
Manganese(III) fluoride fluorinates organic compounds including aromatic hydrocarbons, cyclobutenes, and fullerenes.
On heating, MnF3 decomposes to manganese(II) fluoride
Manganese(II) fluoride
Manganese fluoride is the chemical compound composed of manganese and fluoride with the formula MnF2. It is a light pink crystalline solid, the light pink color being characteristic for manganese compounds. It is made by treating manganese and diverse compounds of manganese in hydrofluoric acid. ...
.
Related Mn(III) compounds
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 synthesisOrganic synthesis
Organic synthesis is a special branch of chemical synthesis and is concerned with the construction of organic compounds via organic reactions. Organic molecules can often contain a higher level of complexity compared to purely inorganic compounds, so the synthesis of organic compounds has...
. MnF3 is Lewis acidic and forms a variety of derivatives. Two examples are K2MnF3(SO4) and K2MnF5.
Safety considerations
Like other reactive inorganic fluorides, MnF3 should be stored in a polyethylene bottle and contact with skin or any other moist area avoided due to the formation of Hydrofluoric acidHydrofluoric acid
Hydrofluoric acid is a solution of hydrogen fluoride in water. It is a valued source of fluorine and is the precursor to numerous pharmaceuticals such as fluoxetine and diverse materials such as PTFE ....
on hydrolysis.
See also
CoF3Cobalt(III) fluoride
Cobalt fluoride is the inorganic compound with the formula CoF3. This highly reactive, hygroscopic brown solid is used to synthesize organofluorine compounds...
, another fluorinating agent based on a transition metal in an oxidising +3 state.
Further reading
- Novel syntheses of some binary fluorides: the role of anhydrous hydrogen fluoride Acta Chim. Slov. 1999, 46(2), pp. 229–238 , Zoran Mazej, Karel Lutar and Boris Žemva
- Knudsen Cell mass spectrometry study of Manganese Trifluoride vaporisation , High temperature corrosion and materials chemistry IV: proceedings of the International Symposium , pp. 521–525 , google books