Activation of an Au−Cl Bond by a Pendent Sb^III Lewis Acid: Impact on Structure and Catalytic Activity

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• 作者：J. Stuart Jones and Prof. Dr. Fran&ccedil ; ois P. Gabbai
• 刊名：Chemistry - A European Journal
• 出版年：2017
• 出版时间：January 23, 2017
• 年：2017
• 卷：23
• 期：5
• 页码：1136-1144
• 全文大小：1773K
• ISSN：1521-3765

文摘

With the objective of identifying new coordination modes of ambiphilic ligands, we have investigated the bidentate Sb/P ligands (o-(Ph₂P)C₆H₄)SbCl₂ (L^Cl) and (o-(Ph₂P)C₆H₄)SbPh₂ (L^Ph). Reaction of these ligands with (tht)AuCl affords the monoligated species L^ClAuCl (1) and L^PhAuCl (2), respectively, in which the antimony centers are only weakly engaged with the coordinated gold atom. Treatment of 1 with PPh₃ induces an intramolecular transfer of a chloride ligand from gold to antimony to form the zwitterionic species o-(Cl₃Sb)C₆H₄(Ph₂P)Au(PPh₃) (3). Natural bond orbital (NBO) calculations show that the antimony and gold centers are involved in weak Sb→Au and Au→Sb interactions, the latter reflecting the Lewis acidity of the pendent antimony group. Finally, we demonstrate that the ability of the antimony center in 1 to abstract a gold-bound chloride in the presence of a Lewis basic substrate may be utilized to activate the gold center for the electrophilic cycloisomerization of propargylic amides.