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(Benzene)chromium(0) tricarbonyl

Names
IUPAC name (benzene)tricarbonylchromium
Other names benzene tricarbonyl chromium, (benzene)chromium tricarbonyl, Benchrotrene, pi-benzenetricarbonylchromium
Identifiers
CAS Number	12082-08-5
3D model (JSmol)	Interactive image
ChemSpider	9130108
ECHA InfoCard	100.031.939
EC Number	235-146-6
PubChem CID	10954891
InChI InChI=1S/C6H6.3CO.Cr/c1-2-4-6-5-3-1;3*1-2;/h1-6H;;;;Key: WVSBQYMJNMJHIM-UHFFFAOYSA-N InChI=1/C6H6.3CO.Cr/c1-2-4-6-5-3-1;3*1-2;/h1-6H;;;;Key: WVSBQYMJNMJHIM-UHFFFAOYAR
SMILES .#.#.#.c1ccccc1
Properties
Chemical formula	Cr(C6H6)(CO)3
Molar mass	214.14 g/mol
Appearance	solid yellow crystals
Melting point	163 to 166 °C (325 to 331 °F; 436 to 439 K)
Solubility in water	nonsoluble
Solubility	THF, ether, benzene
Structure
Coordination geometry	tetrahedral, "piano stool"
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	Harmful through inhalation, contact with skin, or swallowed
GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H302, H312, H332
Precautionary statements	P261, P264, P270, P271, P280, P301+P312, P302+P352, P304+P312, P304+P340, P312, P322, P330, P363, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). N verify (what is  ?) Infobox references

(Benzene)chromium tricarbonyl is an organometallic compound with the formula Cr(C₆H₆)(CO)₃. This yellow crystalline solid compound is soluble in common nonpolar organic solvents. The molecule adopts a geometry known as “piano stool” because of the planar arrangement of the aryl group and the presence of three CO ligands as "legs" on the chromium-bond axis.

Preparation

(Benzene)tricarbonylchromium was first reported in 1957 by Fischer and Öfele, who prepared the compound by the carbonylation of bis(benzene)chromium. They obtained mainly chromium carbonyl (Cr(CO)₆) and traces of Cr(C₆H₆)(CO)₃. The synthesis was optimized through the reaction of Cr(CO)₆ and Cr(C₆H₆)₂. For commercial purposes, a reaction of Cr(CO)₆ and benzene is used:

Cr(CO)₆ + C₆H₆ → Cr(C₆H₆)(CO)₃ + 3 CO

Applications

Complexes of the type (Arene)Cr(CO)₃ have been well investigated as reagents in organic synthesis.. The aromatic ring of (benzene)tricarbonylchromium is substantially more electrophilic than benzene itself, allowing it to undergo nucleophilic addition reactions.

It is also more acidic, undergoing lithiation upon treatment with n-butyllithium. The resulting organolithium compound can then be used as a nucleophile in various reactions, for example, with trimethylsilyl chloride:

(Benzene)tricarbonylchromium is a useful catalyst for the hydrogenation of 1,3-dienes. The product alkene results from 1,4-addition of hydrogen. The complex does not hydrogenate isolated double bonds.

References

1. Gilbert T. M. Bauer C. B., Rogers R. D. (1996). "Structures of (η-benzene dimethylacetal)- and (η-benzene diethylacetal)chromium tricarbonyl: structural evidence for the near-electroneutrality of the dialkylacetal substituent". Journal of Chemical Crystallography. 26 (5): 355. doi:10.1007/BF01677100. S2CID 91957129.
2. Fischer, Ernst Otto; Őfele, Karl. (1957). “Über Aromatenkomplexe von Metallen, XIII Benzol-Chrom-Tricarbonyl,” Chemische Berichte, 90, 2532-5. doi:10.1002/cber.19570901117.
3. E. Peter Kündig (2004). "Synthesis of Transition Metal η-Arene Complexes". Topics Organomet Chem. Topics in Organometallic Chemistry. 7: 3–20. doi:10.1007/b94489. ISBN 978-3-540-01604-5.
4. Herndon, James W; Laurent, Stéphane E. (2008). “(η-Benzene)tricarbonylchromium,” in Encyclopedia of Reagents for Organic Synthesis, John Wiley & Sons, Chichester, 2008. doi:10.1002/047084289X.rb025.pub2. Article Online Posting Date: March 15, 2009

• Half sandwich compounds
• Organochromium compounds
• Carbonyl complexes