Английская Википедия:(Benzene)chromium tricarbonyl

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Шаблон:Chembox (Benzene)chromium tricarbonyl is an organometallic compound with the formula Шаблон:Nowrap. 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

(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)Шаблон:Sub) and traces of Cr(CШаблон:SubHШаблон:Sub)(CO)Шаблон:Sub. The synthesis was optimized through the reaction of Cr(CO)Шаблон:Sub and Cr(CШаблон:SubHШаблон:Sub)Шаблон:Sub. For commercial purposes, a reaction of Cr(CO)Шаблон:Sub and benzene is used:

Cr(CO)Шаблон:Sub + CШаблон:SubHШаблон:Sub → Cr(CШаблон:SubHШаблон:Sub)(CO)Шаблон:Sub + 3 CO

Applications

Complexes of the type (Arene)Cr(CO)3 have been well investigated as reagents in organic synthesis..[3] The aromatic ring of (benzene)tricarbonylchromium is substantially more electrophilic than benzene itself, allowing it to undergo nucleophilic addition reactions.[4]

Файл:(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:

Файл:(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

  1. Шаблон:Cite journal
  2. Fischer, Ernst Otto; Őfele, Karl. (1957). “Über Aromatenkomplexe von Metallen, XIII Benzol-Chrom-Tricarbonyl,” Chemische Berichte, 90, 2532-5. Шаблон:Doi.
  3. Шаблон:Cite journal
  4. Herndon, James W; Laurent, Stéphane E. (2008). “(ηШаблон:Sup-Benzene)tricarbonylchromium,” in Encyclopedia of Reagents for Organic Synthesis, John Wiley & Sons, Chichester, 2008. Шаблон:Doi. Article Online Posting Date: March 15, 2009

Шаблон:Chromium compounds