Abstract
The photochemical oxidation of CpW(CO)3Cl (Cp = η5-C6H5) by carbon tetrachloride and other polychlorocarbons affords CpW(CO)2Cl3. The sole photoprocess is dissociation of CO from the complex to give CpW(CO)2Cl. The major pathway of the oxidation involves the net transfer of two halogen atoms from one halocarbon molecule to the unsaturated metal complex. Pathways involving the formation of trichloromethyl radical were shown to be unimportant. In a related reaction, the photooxidation of Fe(CO)5 in carbon tetrachloride gives FeCl2, tetrachloroethylene, tar, and minor amounts of hexachloroethane. As in the CpW(CO)3Cl system, trichloromethyl radical is produced in, at most, only minor amounts. The reaction proceeds through an iron dichlorocarbene intermediate. Evidence for such an intermediate includes formation of isocyanides, phosgene, and thiophosgene when the oxidation is carried out in the presence of primary amines, dioxygen, and sulfur, respectively. In addition, tetrachloroethylene forms in neat carbon tetrachloride. Various alternative explanations for the above phenomena are considered and found unsatisfactory. The iron carbene species is proposed to arise via oxidative addition of carbon tetrachloride to photolytically generated Fe(CO)4, followed by α-chlorine elimination. Degradation of the complex can then result in either dimerization or telomerization of the dichlorocarbene moiety. The CpW(LO)3Cl system is believed to follow an analogous pathway.
| Original language | English |
|---|---|
| Pages (from-to) | 449-456 |
| Number of pages | 8 |
| Journal | Organometallics |
| Volume | 3 |
| Issue number | 3 |
| Publication status | Published - 1984 |
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ASJC Scopus subject areas
- Inorganic Chemistry
- Organic Chemistry
Cite this
Mechanism of the photochemical oxidation of Fe(CO)5 and CpW(CO)3Cl (Cp = η5-C5H5) by chlorocarbons. / Goldman, Alan S; Tyler, David R.
In: Organometallics, Vol. 3, No. 3, 1984, p. 449-456.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Mechanism of the photochemical oxidation of Fe(CO)5 and CpW(CO)3Cl (Cp = η5-C5H5) by chlorocarbons
AU - Goldman, Alan S
AU - Tyler, David R.
PY - 1984
Y1 - 1984
N2 - The photochemical oxidation of CpW(CO)3Cl (Cp = η5-C6H5) by carbon tetrachloride and other polychlorocarbons affords CpW(CO)2Cl3. The sole photoprocess is dissociation of CO from the complex to give CpW(CO)2Cl. The major pathway of the oxidation involves the net transfer of two halogen atoms from one halocarbon molecule to the unsaturated metal complex. Pathways involving the formation of trichloromethyl radical were shown to be unimportant. In a related reaction, the photooxidation of Fe(CO)5 in carbon tetrachloride gives FeCl2, tetrachloroethylene, tar, and minor amounts of hexachloroethane. As in the CpW(CO)3Cl system, trichloromethyl radical is produced in, at most, only minor amounts. The reaction proceeds through an iron dichlorocarbene intermediate. Evidence for such an intermediate includes formation of isocyanides, phosgene, and thiophosgene when the oxidation is carried out in the presence of primary amines, dioxygen, and sulfur, respectively. In addition, tetrachloroethylene forms in neat carbon tetrachloride. Various alternative explanations for the above phenomena are considered and found unsatisfactory. The iron carbene species is proposed to arise via oxidative addition of carbon tetrachloride to photolytically generated Fe(CO)4, followed by α-chlorine elimination. Degradation of the complex can then result in either dimerization or telomerization of the dichlorocarbene moiety. The CpW(LO)3Cl system is believed to follow an analogous pathway.
AB - The photochemical oxidation of CpW(CO)3Cl (Cp = η5-C6H5) by carbon tetrachloride and other polychlorocarbons affords CpW(CO)2Cl3. The sole photoprocess is dissociation of CO from the complex to give CpW(CO)2Cl. The major pathway of the oxidation involves the net transfer of two halogen atoms from one halocarbon molecule to the unsaturated metal complex. Pathways involving the formation of trichloromethyl radical were shown to be unimportant. In a related reaction, the photooxidation of Fe(CO)5 in carbon tetrachloride gives FeCl2, tetrachloroethylene, tar, and minor amounts of hexachloroethane. As in the CpW(CO)3Cl system, trichloromethyl radical is produced in, at most, only minor amounts. The reaction proceeds through an iron dichlorocarbene intermediate. Evidence for such an intermediate includes formation of isocyanides, phosgene, and thiophosgene when the oxidation is carried out in the presence of primary amines, dioxygen, and sulfur, respectively. In addition, tetrachloroethylene forms in neat carbon tetrachloride. Various alternative explanations for the above phenomena are considered and found unsatisfactory. The iron carbene species is proposed to arise via oxidative addition of carbon tetrachloride to photolytically generated Fe(CO)4, followed by α-chlorine elimination. Degradation of the complex can then result in either dimerization or telomerization of the dichlorocarbene moiety. The CpW(LO)3Cl system is believed to follow an analogous pathway.
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M3 - Article
VL - 3
SP - 449
EP - 456
JO - Organometallics
JF - Organometallics
SN - 0276-7333
IS - 3
ER -