Manganese (III) acetylacetonate

Structural formula
General
Surname	Manganese (III) acetylacetonate
other names	Trisacetylacetone atomanganese (III); Manganese (III) pentane-2,4-dione; Tris (2,4-pentanedionato) manganese (III); Mn (acac) 3 ;
Molecular formula	C 15 H 21 MnO 6
Brief description	black solid
External identifiers / databases
EC number	238-188-3
ECHA InfoCard	100.034.701
PubChem	6477710
ChemSpider	76062
Wikidata	Q1890171
properties
Molar mass	352.3 g mol −1
Physical state	firmly
Melting point	159–161 ° C (decomposition)
safety instructions
GHS labeling of hazardous substances hydrate Caution
H and P phrases	H: 302-315-319-335
	P: 261-305 + 351 + 338
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Manganese (III) acetylacetonate (Mn (acac) ₃ ) is a complex of manganese in the +3 oxidation state, with acetylacetonate as a ligand .

Extraction and presentation

Manganese (III) acetylacetonate is made from a manganese (II) salt, potassium permanganate and acetylacetone.

The reaction initially produces manganese (II) acetylacetonate as an intermediate:

{\ displaystyle \ mathrm {Mn ^ {2 +} + 2 \ CH_ {3} COCH_ {2} COCH_ {3} \ longrightarrow}}

{\ displaystyle \ mathrm {2 \ H ^ {+} + Mn (CH_ {3} COCHCOCH_ {3}) _ {2}}}

The reaction of Mn (II) and Mn (VII) produces Mn (III):

{\ displaystyle \ mathrm {Mn (VII) +4 \ Mn (II) \ longrightarrow 5 \ Mn (III)}}

Overall reaction:

{\ displaystyle \ mathrm {4 \ Mn ^ {2 +} + MnO_ {4} ^ {-} + 15 \ CH_ {3} COCH_ {2} COCH_ {3} \ longrightarrow}}

{\ displaystyle \ mathrm {5 \ Mn (CH_ {3} COCHCOCH_ {3}) _ {3} +4 \ H_ {2} O + 7 \ H ^ {+}}}

The acid formed is buffered by adding sodium acetate . Furthermore, it shifts the equilibrium in the enol-keto-tautomerism of acetyl acetone.

Due to the weakly basic property of the sodium acetate, the enol form is deprotonated and the acetylacetone is converted into its anionic form. It thus stabilizes the d ⁴ -configured manganese ion through complex formation.

properties

Manganese (III) acetylacetonate is a black, crystalline powder that is insoluble in water. According to the electronic structure, it forms a high spin complex . The structure is octahedrally distorted due to the Jahn-Teller effect . This can either be octahedral-compressed or octahedral-stretched. When stretched, the lengths of two Mn-O bonds are 2.12 Å, with the other four being only 1.93 Å. When compressed, the lengths of two Mn-O bonds are 1.95 Å while the other four bond lengths are 2.00 Å.

use

Manganese (III) acetylacetonate is used to oxidize phenols , β-dicarbonyl compounds and thiols .

literature

J. Derek Woollins: Inorganic Experiments. Wiley-VCH, Weinheim 1994, ISBN 3-527-29253-5 , pp. 118-119.
F. Albert Cotton, Geoffrey Wilkinson, Carlos A. Murillo, Manfred Bochmann: Advanced Inorganic Chemistry. 6th ed. Wiley-Interscience, New York 1999, ISBN 0-471-19957-5 .

Individual evidence

↑ ^a ^b ^c ^d ^e ^f Datasheet Manganese (III) acetylacetonate from Sigma-Aldrich , accessed on June 18, 2012 ( PDF ).
^ AF Holleman , E. Wiberg , N. Wiberg : Textbook of Inorganic Chemistry . 102nd edition. Walter de Gruyter, Berlin 2007, ISBN 978-3-11-017770-1 , pp. 1616-1617.

[Sigma-1] ↑ ^a ^b ^c ^d ^e ^f Datasheet Manganese (III) acetylacetonate from Sigma-Aldrich , accessed on June 18, 2012 ( PDF ).

[HoWi2007-2] AF Holleman , E. Wiberg , N. Wiberg : Textbook of Inorganic Chemistry . 102nd edition. Walter de Gruyter, Berlin 2007, ISBN 978-3-11-017770-1 , pp. 1616-1617.