(Benzene)chromium tricarbonyl

From Wikipedia, the free encyclopedia
Jump to: navigation, search
(Benzene)chromium(0) tricarbonyl
Benzenetricarbonylchromium.svg
(benzene)chromium-tricarbonyl-from-xtal-1987-3D-balls.png
Names
IUPAC name
(benzene)tricarbonylchromium
Other names
benzene tricarbonyl chromium, (benzene)chromium tricarbonyl, Benchrotrene, pi-benzenetricarbonylchromium
Identifiers
12082-08-5 N
ChemSpider 9130108 YesY
Jmol 3D model Interactive image
Properties
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)
nonsoluble
Solubility THF, ether, benzene
Structure
tetrahedral, "piano stool"
Hazards
Main hazards Harmful through inhalation, contact with skin, or swallowed
R-phrases 20/21/22
S-phrases 36/37
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YesYN ?)
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.[1]

Preparation[edit]

(Benzene)tricarbonylchromium was first reported in 1957 by Fischer and Öfele, who prepared the compound by the carbonylation of bis(benzene)chromium.[2] 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[edit]

The aromatic ring of (benzene)tricarbonylchromium is substantially more electrophilic than benzene itself, allowing it to undergo nucleophilic addition reactions.[3]

(Benzene)chromiumtricarbonyl electrophile nucleophilic carbonylation.png

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)chromiumtricarbonyl lithiation TMS.png

(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[edit]

  1. ^ Gilbert T. M. Bauer C. B., Rogers R. D. (1996). "Structures of (η6-benzene dimethylacetal)- and (η6-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. 
  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. ^ Herndon, James W; Laurent, Stéphane E. (2008). “(η6-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