Structural, Computational, and Spectroscopic Investigation of [Pd(κ3-1,1‿bis(di-tert-butylphosphino)ferrocenediyl)X]+ (X = Cl, Br, I) Compounds

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• 作者：Brittany L. Blass ; Raúl Hernández Sánchez ; Victoria A. Decker ; Michael J. Robinson ; Nicholas A. Piro ; W. Scott Kassel ; Paula L. Diaconescu ; Chip Nataro
• 刊名：Organometallics
• 出版年：2016
• 出版时间：February 22, 2016
• 年：2016
• 卷：35
• 期：4
• 页码：462-470
• 全文大小：455K
• ISSN：1520-6041

文摘

The reaction of [Pd(dtbpf)Cl₂] (dtbpf = 1,1′-bis(di-tert-butylphosphino)ferrocene) with sodium bromide yields [Pd(dtbpf)Br][Br], which displays an interaction between the iron and palladium atoms. The structure of this compound has been obtained and is compared to those of the previously reported [Pd(dtbpf)X]⁺ (X = Cl, I) analogues. Similar to [Pd(dtbpf)Cl]⁺, [Pd(dtbpf)Br]⁺ appears to undergo a solid-state isomerization at low temperature to a species in which the Fe–Pd interaction is disrupted. In addition to ¹H and ³¹P{¹H} NMR and visible spectroscopy, the [Pd(dtbpf)X]⁺ (X = Cl, Br) compounds were also characterized by zero-field ⁵⁷Fe Mössbauer spectroscopy. DFT calculations on [Pd(dtbpf)X]⁺ (X = Cl, Br, I) show that the Fe–Pd interaction is weak and noncovalent and that the strength of the interaction decreases as the halide becomes larger. A related trend is noted in the potential at which oxidation of the iron center occurs; the larger the halide, the less positive the potential at which oxidation occurs. Finally, the catalytic activity of [Pd(dtbpf)X]⁺ (X = Cl, Br, I) in the arylation of an aromatic ketone was examined and compared to the activity of [Pd(dtbpf)Cl₂].