Communication
Dodecacarbonyltetracobalt Catalysis in the Thermal Pauson–Khand Reaction
Marie E. Krafft Prof.,
Llorente V. R. Boñaga,
Marie E. Krafft Prof.
Department of Chemistry The Florida State University Tallahassee, FL 32306-4390 (USA) Fax: (+1) 850-644-8281
Search for more papers by this authorLlorente V. R. Boñaga
Department of Chemistry The Florida State University Tallahassee, FL 32306-4390 (USA) Fax: (+1) 850-644-8281
Search for more papers by this authorMarie E. Krafft Prof.,
Llorente V. R. Boñaga,
Marie E. Krafft Prof.
Department of Chemistry The Florida State University Tallahassee, FL 32306-4390 (USA) Fax: (+1) 850-644-8281
Search for more papers by this authorLlorente V. R. Boñaga
Department of Chemistry The Florida State University Tallahassee, FL 32306-4390 (USA) Fax: (+1) 850-644-8281
Search for more papers by this authorFirst published: 13 October 2000
Citations: 47
This work was supported by the National Science Foundation and the donors to the Krafft Research Fund.
Abstract
Contrary to common belief [Co4(CO)12] does catalyze the Pauson–Khand reaction under practical laboratory conditions (70°C, 1 atm of CO) [Eq. (1)]. Its catalytic efficiency was further enhanced by an additive (cyclohexylamine, pyridine), which possibly facilitated its disproportionation into and promoted preservation of the catalytically active cobalt species. This is the first practical procedure using the commercially available and more stable [Co4(CO)12] cluster as a catalyst precursor.
References
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- 19 It was reported that under 1 atm of CO, at 53 °C a hexane solution of [Co4(CO)12] would be converted to a solution in which 50 % of the cobalt content is present as [Co2(CO)8] (t1/2=160 days).[10b]
- 20 Upon exposure to air, [Co4(CO)12] oxidizes to a purple CoII species but this proceeds at an appreciably slower rate than [Co2(CO)8]:
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- 21 T. Sugihara, M. Yamaguchi, J. Am. Chem. Soc. 1998, 120, 10 782. Optimal catalysis of the methylidenetricobalt nonacarbonyl cluster was achieved in toluene at 120 °C under 7 atm of CO. It is of interest that the use of the parent cobalt cluster, [Co4(CO)12], was not reported in these studies.
- 22 Highly purified [Co2(CO)8] and [Co4(CO)12] were reported by Jeong et al. to undergo spontaneous ignition upon exposure to air; ref. [8b]. See also ref. [5b].
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