Enhanced Stability of a Paramagnetic Palladium Complex Promoted by Interactions with Ethynyl Substrates

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• 作者：Sophie Dal Molin ; Cyril Cugnet ; David Brevet ; Dominique Lucas ; Yves Mugnier ; Daniel Fortin ; Ren&eacute ; T. Boer&eacute ; Pierre D. Harvey
• 刊名：Organometallics
• 出版年：2007
• 出版时间：October 8, 2007
• 年：2007
• 卷：26
• 期：21
• 页码：5209 - 5215
• 全文大小：365K
• 年卷期：v.26,no.21(October 8, 2007)
• ISSN：1520-6041

文摘

The highly reactive palladium-centered radical cluster [Pd₃(dppm)₃(CO)]⁺ exhibits only a limitedstability in solution at room temperature (about an hour). This stability can be extended significantly toseveral hours by adding organic substrates such as the symmetric and asymmetric alkynes Ph-CC-Hand MeO₂C-CC-CO₂Me, which reversibly bind to the Pd₃ triangle. The presence of the substrateinside the cavity protects the palladium centers from reacting with the "outside world", hence enhancingthe stability. Both adducts are stable as the cluster is always totally recovered. The paramagnetic complexesalong with their corresponding dications were characterized by EPR, variable-temperature ³¹P NMR,UV-vis and MALDI-TOF spectroscopy, and electrochemistry. For the MeO₂C-CC-CO₂Me/[Pd₃(dppm)₃(CO)]²⁺ complex, the analysis of the low-temperature ³¹P NMR spectra strongly suggests a majorstructure modification of the ligand and substrate with respect to the starting materials.