A Chiral Phosphoramidite beyond Monodentate Coordination: Secondary π-Interactions Turn a Dangling Aryl into a Two-, Four-, or Six-Electron Donor in d6 and d8 Complexes

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• 作者：Igor S. Mikhel ; Heinz Rü ; egger ; Pietro Butti ; Francesco Camponovo ; Dominik Huber ; Antonio Mezzetti
• 刊名：Organometallics
• 出版年：2008
• 出版时间：July 14, 2008
• 年：2008
• 卷：27
• 期：13
• 页码：2937 - 2948
• 全文大小：310K
• 年卷期：v.27,no.13(July 14, 2008)
• ISSN：1520-6041

文摘

A study of the secondary interactions involving a pendant phenethyl group (NCH(CH₃)Ph) of (S_a,R_C,R_C)-O,O′-[1,1′-binaphthyl-2,2′-diyl]-N,N′-bis[1-phenylethyl]phosphoramidite (1) in d⁸ and d⁶ metal complexes is reported. A 1,2-η-phenyl interaction is found in [Pd(η³-allyl)(1,2-η-Ph-1-κP)]⁺ (3), as indicated by NMR spectroscopy and by an X-ray study. The Rh(I) complexes [RhCl(NBD)(1-κP)] (4a) and [RhCl(COD)(1-κP)] (4b) were prepared, and their X-ray structures were determined. Chloride abstraction from 4a and 4b gave the corresponding cations [Rh(NBD)(1,2-η-Ph-1-κP)]⁺ (5a) and [Rh(COD)(1,2-η-Ph-1-κP)]⁺ (5b), which were fully characterized. Besides NMR spectroscopic data, the 1,2-η-phenyl interaction is supported by an X-ray study of 5a. Upon standing in MeOH solution, 5b undergoes loss of the COD and forms [Rh(1-κP)(η⁶-Ph-1-κP)]⁺ (6), whose η⁶-arene coordination was studied by NMR spectroscopy and by X-ray diffraction. For the sake of comparison with the d⁸ complex 6, the crystal structure of the previously reported d⁶ analogue [RuCl₂(η⁶-Ph-1-κP)]⁺ (7) was determined. This study shows that secondary π-arene−metal interactions turn phosphoramidite 1 to a four-, six-, or eight-electron donor, with increasing bond strength in this order.