Chromium (II) acetate

Crystal structure
	__ Cr __ C __ O 2− __ H +
General
Surname	Chromium (II) acetate
Ratio formula	C 8 H 16 Cr 2 O 10
Brief description	light brown solid (anhydrous); red solid (hydrate);
External identifiers / databases
EC number	695-958-5
ECHA InfoCard	100.224.848
PubChem	120304
Wikidata	Q419517
properties
Molar mass	376.20 g mol −1
Physical state	firmly
density	1.79 g cm −3
solubility	practically insoluble in water and ether, soluble in hot water; slightly soluble in ethanol;
safety instructions
GHS labeling of hazardous substances	no GHS pictograms
	no GHS pictograms
H and P phrases	H: no H-phrases
	P: no P-phrases
Toxicological data	11260 mg kg −1 ( LD 50 , rat , oral )
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Chromium (II) acetate is a chemical compound of chromium from the group of acetates . It is usually obtained as a dimeric dihydrate with the constitutional formula. It therefore consists of two chromium (II) ions, four acetate residues and two molecules of water. ${\ displaystyle {\ ce {[Cr (CH3COO) 2] 2. 2 H2O}}}$

history

The compound was first mentioned in 1844 in a work by Eugene Peligot , who noticed that red transparent crystals precipitated from blue solutions of chromium (II) compounds when potassium or sodium acetate was added, and that these crystals rapidly decomposed in air. However, it was not until 1950 that attention was drawn to the different types of bond compared to other chromium (II) salts. In 1953 it was discovered that the compound is isomorphic to copper (II) acetate hydrate .

Extraction and presentation

Chromium (II) acetate can be obtained by reacting a chromium (II) compound (e.g. chromium (II) chloride ) with sodium acetate .

{\ displaystyle {\ ce {2 CrCl2 + 4 CH3COONa + 2 H2O -> [Cr (CH3COO) 2] 2. 2 H2O + 4 NaCl}}}

When the hydrate is dried over phosphorus (V) oxide at 100 ° C. , the anhydrate is formed.

properties

Chromium (II) acetate is a dimeric dihydrate, a diamagnetic red solid with a monoclinic crystal structure. In this case, the two chromium atoms form a quadruple bond between them, which is very unusual for metals (one σ, two π and one δ electron bond ). This can be explained with the four unpaired electrons of the chromium (II) ions, with the acetate residues stabilizing the complex. The bond distance between the chromium ions is very short at 2.362 Å.

It can only be kept dry in air for a few hours and indefinitely under nitrogen. The drying over phosphorus pentoxide at 100 ° C leads to the release of the complex-bound crystal water with a change in color to brown and an increase in air sensitivity.

use

Chromium (II) acetate is used as a reducing agent in organic syntheses.

It can also be used to produce other chromium (II) salts and to remove oxygen in gas analyzes.

Individual evidence

↑ LR Ocone and BP Block: Anhydrous chromium (II) acetate, chromium (II) acetate 1-hydrate, and bis (2,4-pentandionato) chromium (II) . In: Henry F. Holtzclaw, Jr. (Ed.): Inorganic Syntheses . tape 8 . McGraw-Hill Book Company, Inc., 1966, pp. 125-132 (English).
↑ ^a ^b ^c ^d ^e data sheet Chromium (II) acetate, dimer monohydrate from Sigma-Aldrich , accessed on May 25, 2017 ( PDF ).
^ ^A ^b ^c Dale L. Perry: Handbook of Inorganic Compounds, Second Edition . Taylor & Francis US, 2011, ISBN 1-4398-1461-9 , pp. 478 ( limited preview in Google Book search).
^ ^A ^b Arnold Frederic Holleman, Egon Wiberg, Nils Wiberg: Holleman-Wiberg's Inorganic Chemistry . Academic Press, 2001, ISBN 0-12-352651-5 , pp. 1380 ( limited preview in Google Book search).
↑ ^a ^b ^c Georg Brauer: Handbook of preparative inorganic chemistry . 3., reworked. Edition. tape III . Enke, Stuttgart 1981, ISBN 3-432-87823-0 , pp. 1511 .
^ F. Albert Cotton, Carlos A. Murillo, Richard A. Walton: Multiple Bonds between Metal Atoms . Springer, 2005, ISBN 0-387-25084-0 , pp. 10 ( limited preview in Google Book search).
^ ^A ^b Uwe Böhme: Chemistry for engineers for dummies . John Wiley & Sons, 2012, ISBN 3-527-70682-8 , pp. 276 ( limited preview in Google Book search).
↑ David R. Lide: CRC Handbook of Chemistry and Physics 2012-2013 . CRC Press, 2012, ISBN 1-4398-8049-2 , pp. 4–58 ( limited preview in Google Book Search).
^ Hans Kricheldorf R. Kricheldorf, Oskar Nuyken, Graham Swift: Handbook of Polymer Synthesis: Second Edition . CRC Press, 2005, ISBN 0-8247-5473-5 , pp. 816 ( limited preview in Google Book search).

[IS8-1] LR Ocone and BP Block: Anhydrous chromium (II) acetate, chromium (II) acetate 1-hydrate, and bis (2,4-pentandionato) chromium (II) . In: Henry F. Holtzclaw, Jr. (Ed.): Inorganic Syntheses . tape 8 . McGraw-Hill Book Company, Inc., 1966, pp. 125-132 (English).

[Sigma-2] ↑ ^a ^b ^c ^d ^e data sheet Chromium (II) acetate, dimer monohydrate from Sigma-Aldrich , accessed on May 25, 2017 ( PDF ).

[Dale_L._Perry-3] A ^b ^c Dale L. Perry: Handbook of Inorganic Compounds, Second Edition . Taylor & Francis US, 2011, ISBN 1-4398-1461-9 , pp. 478 ( limited preview in Google Book search).

[HoWi-4] A ^b Arnold Frederic Holleman, Egon Wiberg, Nils Wiberg: Holleman-Wiberg's Inorganic Chemistry . Academic Press, 2001, ISBN 0-12-352651-5 , pp. 1380 ( limited preview in Google Book search).

[brauer-5] Georg Brauer: Handbook of preparative inorganic chemistry . 3., reworked. Edition. tape III . Enke, Stuttgart 1981, ISBN 3-432-87823-0 , pp. 1511 .

[F._Albert_Cotton,_Carlos_A._Murillo,_Richard_A._Walton-6] F. Albert Cotton, Carlos A. Murillo, Richard A. Walton: Multiple Bonds between Metal Atoms . Springer, 2005, ISBN 0-387-25084-0 , pp. 10 ( limited preview in Google Book search).

[Uwe_Böhme-7] A ^b Uwe Böhme: Chemistry for engineers for dummies . John Wiley & Sons, 2012, ISBN 3-527-70682-8 , pp. 276 ( limited preview in Google Book search).

[David_R._Lide-8] David R. Lide: CRC Handbook of Chemistry and Physics 2012-2013 . CRC Press, 2012, ISBN 1-4398-8049-2 , pp. 4–58 ( limited preview in Google Book Search).

[Hans_Kricheldorf_R._Kricheldorf,_Oskar_Nuyken,_Graham_Swift-9] Hans Kricheldorf R. Kricheldorf, Oskar Nuyken, Graham Swift: Handbook of Polymer Synthesis: Second Edition . CRC Press, 2005, ISBN 0-8247-5473-5 , pp. 816 ( limited preview in Google Book search).