Alkyne Dicobalt Carbonyl Complexes with Sulfide Ligands. Synthesis, Crystal Structure, and Dynamic Behavior
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- 作者：Xavier Verdaguer ; Albert Moyano ; Miquel A. Pericà ; s ; Antoni Riera ; Angel Alvarez-Larena ; and Joan-F. Piniella
- 刊名：Organometallics
- 出版年：1999
- 出版时间：October 11, 1999
- 年：1999
- 卷：18
- 期：21
- 页码：4275 - 4285
- 全文大小：282K
- 年卷期：v.18,no.21(October 11, 1999)
- ISSN：1520-6041
文摘
Hexacarbonyl dicobalt complex of bis(tert-butylsulfonylethyne) [Co2(
-ButSO2C)2(CO)6, 3]experiences a thermally induced ligand exchange process with methyl p-tolyl sulfide, dibenzylsulfide, and diethyl sulfide to give the corresponding stable sulfide complexes [Co2(-ButSO2C)2(CO)5SR2] 4, 5, and 6, respectively, in good yield (59-65%). The reaction withtetrahydrothiophene gives a disubstituted complex 7 in 74% yield. Oxathiane 9, derivedfrom (+)-(2R)-10-mercaptoisoborneol, also reacts with 3 to generate a chiral sulfide complex8 (58%). The solid-state structures of 5 and 8 have been established by X-ray crystallographyand reveal the preference of the incoming sulfur ligand to occupy an equatorial coordinationsite. Further structural studies on 5 have been performed by low-temperature 1H NMRanalysis and by theoretical procedures at the PM3(tm) level of theory. Analysis of the low-temperature 1H NMR spectrum of 5 shows a signal splitting consistent with the freezing ofan equilibrium between two equatorially coordinated sulfides, and the computational studyof the different isomers of 5 shows that the equatorially coordinated complex is 3.9 kcalmol-1 lower in energy than the most stable axially coordinated one, in agreement with solid-state and solution studies. Finally, ligand exchange experiments have been performed inorder to provide an explanation for the Pauson-Khand reactivity of alkynes containingancillary sulfide ligands and were found to support the experimentally observed rateenhancements.
-ButSO2C)2(CO)6, 3]experiences a thermally induced ligand exchange process with methyl p-tolyl sulfide, dibenzylsulfide, and diethyl sulfide to give the corresponding stable sulfide complexes [Co2(-ButSO2C)2(CO)5SR2] 4, 5, and 6, respectively, in good yield (59-65%). The reaction withtetrahydrothiophene gives a disubstituted complex 7 in 74% yield. Oxathiane 9, derivedfrom (+)-(2R)-10-mercaptoisoborneol, also reacts with 3 to generate a chiral sulfide complex8 (58%). The solid-state structures of 5 and 8 have been established by X-ray crystallographyand reveal the preference of the incoming sulfur ligand to occupy an equatorial coordinationsite. Further structural studies on 5 have been performed by low-temperature 1H NMRanalysis and by theoretical procedures at the PM3(tm) level of theory. Analysis of the low-temperature 1H NMR spectrum of 5 shows a signal splitting consistent with the freezing ofan equilibrium between two equatorially coordinated sulfides, and the computational studyof the different isomers of 5 shows that the equatorially coordinated complex is 3.9 kcalmol-1 lower in energy than the most stable axially coordinated one, in agreement with solid-state and solution studies. Finally, ligand exchange experiments have been performed inorder to provide an explanation for the Pauson-Khand reactivity of alkynes containingancillary sulfide ligands and were found to support the experimentally observed rateenhancements.