(Benzene)chromium tricarbonyl
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| Names | |||
|---|---|---|---|
| IUPAC name
(benzene)tricarbonylchromium | |||
| Other names
benzene tricarbonyl chromium, (benzene)chromium tricarbonyl, Benchrotrene, pi-benzenetricarbonylchromium | |||
| Identifiers | |||
12082-08-5  | |||
| ChemSpider | 9130108  | ||
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| Jmol-3D images | Image | ||
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| 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 noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa) | |||
| verify (what is: /?) | |||
| Infobox references | |||
chromium-tricarbonyl-from-xtal-1987-3D-balls.png)
(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
(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
The aromatic ring of (benzene)tricarbonylchromium is substantially more electrophilic than benzene itself, allowing it to undergo nucleophilic addition reactions.[3]
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:
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
- ↑ 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.
- ↑ Fischer, Ernst Otto; Őfele, Karl. (1957). “Über Aromatenkomplexe von Metallen, XIII Benzol-Chrom-Tricarbonyl,” Chemische Berichte, 90, 2532-5. doi:10.1002/cber.19570901117.
- ↑ 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