Manganese(III) chloride is the hypothetical
inorganic compound with the formula MnCl
3.
The existence of this
binary
Binary may refer to:
Science and technology Mathematics
* Binary number, a representation of numbers using only two digits (0 and 1)
* Binary function, a function that takes two arguments
* Binary operation, a mathematical operation that ta ...
halide has not been demonstrated. Nonetheless, many derivatives of MnCl
3 are known, such as MnCl
3(THF)
3 and the bench-stable
MnCl3(OPPh3)2. Contrasting with the elusive nature of MnCl
3, trichlorides of the adjacent metals on the
periodic table—
iron(III) chloride,
chromium(III) chloride
Chromium(III) chloride (also called chromic chloride) describes any of several chemical compounds with the formula CrCl3, where can be 0, 5, and 6. The anhydrous compound with the formula CrCl3 is a violet solid. The most common form of the tric ...
, and
technetium(III) chloride—are all isolable compounds.
History of MnCl3 and its adducts
MnCl
3 was claimed to be a dark solid and produced by the reaction of "anhydrous
manganese(III) acetate
Manganese(III) acetate describes a family of materials with the approximate formula Mn(O2CCH3)3. These materials are brown solids that are soluble in acetic acid and water. They are used in organic synthesis as oxidizing agents.
Structure
Altho ...
" and liquid
hydrogen chloride
The compound hydrogen chloride has the chemical formula and as such is a hydrogen halide. At room temperature, it is a colourless gas, which forms white fumes of hydrochloric acid upon contact with atmospheric water vapor. Hydrogen chloride ga ...
at −100 °C and decomposes above -40 °C.
Other claims involved reaction of
manganese(III) oxide, manganese(III) oxide-hydroxide, and basic manganese acetate with
hydrochloric acid
Hydrochloric acid, also known as muriatic acid, is an aqueous solution of hydrogen chloride. It is a colorless solution with a distinctive pungent smell. It is classified as a strong acid
Acid strength is the tendency of an acid, symbol ...
. Given recent investigations however, such claims have been disproved or called into serious doubt.
Specifically, all known compounds containing MnCl
3 are known to be solvent or ligand-stabilized
adduct
An adduct (from the Latin ''adductus'', "drawn toward" alternatively, a contraction of "addition product") is a product of a direct addition of two or more distinct molecules, resulting in a single reaction product containing all atoms of all co ...
s.
Adducts
MnCl
3 can be stabilized by complexation to diverse
Lewis bases, as has been established over the course of many years of study.
Meta stable acetonitrile-solvated Mn(III)Cl
3 can be prepared at room temperature by treating
12O12(OAc)16(H2O)4/nowiki>">n
12O
12(OAc)
16(H
2O)
4/nowiki> with trimethylsilyl chloride
Trimethylsilyl chloride, also known as chlorotrimethylsilane is an organosilicon compound (silyl halide), with the formula (CH3)3SiCl, often abbreviated Me3SiCl or TMSCl. It is a colourless volatile liquid that is stable in the absence of water. I ...
. The treatment of permanganate salts with trimethylsilylchloride generates solutions containing Mn(III)–Cl species for alkene dichlorination reactions; electrocatalytic methods that use Mn(III)–Cl intermediates have been developed for the same purpose.
The reaction of manganese dioxide with hydrochloric acid in tetrahydrofuran
Tetrahydrofuran (THF), or oxolane, is an organic compound with the formula (CH2)4O. The compound is classified as heterocyclic compound, specifically a cyclic ether. It is a colorless, water- miscible organic liquid with low viscosity. It is ...
gives MnCl3(H2O)(THF)2. 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. It forms a hydrat ...
suspended in THF reacts with boron trichloride
Boron trichloride is the inorganic compound with the formula BCl3. This colorless gas is a reagent in organic synthesis. It is highly reactive toward water.
Production and structure
Boron reacts with halogens to give the corresponding trihalides. ...
, giving MnCl3(THF)3 which has the appearance of dark purple prisms. This compound has a monoclinic crystal structure, reacts with water, and decomposes at room temperature.
The most readily handled of this series of adducts is MnCl3(OPPh3)2.
Pentachloromanganate(III)
Another common manganese(III) chloride compound is the pentachloromanganate(III) dianion. It is usually change balanced with counterion(s) like tetraethylammonium
Tetraethylammonium (TEA), () or (Et4N+) is a quaternary ammonium cation consisting of four ethyl groups attached to a central nitrogen atom, and is positively charged. It is a counterion used in the research laboratory to prepare lipophilic salts ...
. The pentachloromanganates are typically green in color, light sensitive, maintain pentacoordination in solution, and have S = 2 ground states at room temperature. Crystal structures of pentachloromanganate indicate the anion is square pyramidal
In molecular geometry, square pyramidal geometry describes the shape of certain Chemical compound, compounds with the formula where L is a ligand. If the ligand atoms were connected, the resulting shape would be that of a Square pyramid, pyram ...
. Tetraethylammonium pentachloromanganate(III), 4N">t4Nsub>2 5">nCl5 can be prepared and isolated by treating suspension of 12O12(OAc)16(H2O)4/nowiki>">n12O12(OAc)16(H2O)4/nowiki> in diethyl ether
Diethyl ether, or simply ether, is an organic compound in the ether class with the formula , sometimes abbreviated as (see Pseudoelement symbols). It is a colourless, highly volatile, sweet-smelling ("ethereal odour"), extremely flammable li ...
with trimethylsilylchloride, collecting the resulting purple solid in the dark, and then treating this solid with 0.6 M solution of tetraethylammonium chloride. The green product is air stable but should be kept in the dark.
Manganese(III) monochloride compounds
Some manganese compounds
Manganese is a chemical element with the symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese is a transition metal with a multifaceted array of industrial alloy use ...
with macrocyclic tetradentate coordination can stabilize the manganese(III) monochloride, Mn(III)–Cl, moiety. Jacobson's catalyst is an example of a coordination compound containing the Mn(III)–Cl moiety and is stabilized by ''N,N,O,O'' coordination from a salen ligand
Salen refers to a tetradentate C2-symmetric ligand synthesized from salicylaldehyde (sal) and ethylenediamine (en). It may also refer to a class of compounds, which are structurally related to the classical salen ligand, primarily bis-Schiff base ...
. Jacobson's catalyst and related Mn(III)–Cl complexes react with O-atom transfer reagents to form high-valent Mn(V)O that are reactive in alkene epoxidation
In organic chemistry, an epoxide is a cyclic ether () with a three-atom ring. This ring approximates an equilateral triangle, which makes it strained, and hence highly reactive, more so than other ethers. They are produced on a large scale ...
. Tetraphenylporphyrin
Tetraphenylporphyrin, abbreviated TPP or H2TPP, is a synthetic heterocyclic compound that resembles naturally occurring porphyrins. Porphyrins are dyes and cofactors found in hemoglobin and cytochromes and are related to chlorophyll and vitamin ...
Mn(III)Cl is a related commercially available compound.
Other manganese(III) chloride complexes
* Bis(triphenylphosphineoxide) manganese(III) chloride
References
{{chlorides
Manganese(III) compounds
Chlorides