含硫醚、亞碸-氮雜環碳烯配位基之有機鉑錯合物的 合成、異構及催化

Synthesis and Catalysis of Thioether- and Sulfoxide- Functionalized N-Heterocyclic Carbene Platinum Complexes

郭泰亨(Tai-Heng Kuo)

指導教授 ： 陳竹亭

國立臺灣大學/理學院/化學研究所/碩士(2013年)

https://doi.org/10.6342/NTU.2013.01098

摘要

一系列的硫醚、亞碸氮雜環碳烯的丙烯基鉑金屬錯合物以(S-NHC-R)Pt(ɳ3-CH2C(Me)CH2)X 以及 (SO-NHC-R)Pt(ɳ3-CH2C(Me)CH2)X (R = Me, Ph, 而 X = Cl, PF6) 的形式已被成功的合成並藉由核磁共振技術和X光結晶學確定其結構。所合成的丙烯基鉑金屬錯合物都具有內與外異構物，且兩者間存在一個平衡。

從二維核磁共振技術中發現，在硫醚氮雜環碳烯的鉑金屬錯合物裡，內、外異構物能經由硫醚基的反轉而互相轉換。在變溫核磁共振光譜中，可以進一步求得其反轉屏障的能量，約為 15-16 kcal/mol。然而在亞碸氮雜環碳烯鉑金屬錯合物裡，卻發現其一維核磁共振氫譜中，骨架氫與氮雜環的訊號跟硫醚氮雜環碳烯的鉑金屬錯合物的訊號非常不一樣，其在258 K到333 K的溫度範圍都呈現尖銳且固定的訊號，可能是因為亞碸氮雜環碳烯鉑金屬錯合物不具有硫醚基的反轉造成這樣的差異。

在加入三苯基磷與吡啶的取代反應中，我們發現即使加了50當量的吡啶仍然無法取代硫醚基供體上的硫原子，但是要取代掉亞碸供體上的硫原子只需要5當量的吡啶。而兩大類的供體都可以被三苯基磷給取代掉，形成新的化合物。在此我們證明了亞碸供體較優越的易變性。

關鍵字

異構 ； 硫醚基 ； 亞碸易變性 ； 有機鉑

並列摘要

Two series of (Thioether-NHC-R)Pt(ɳ3-CH2C(Me)CH2)X and (Sulfoxide-NHC-R)Pt(ɳ3-CH2C(Me)CH2)X (R = Me, Ph, and X = Cl, PF6) complexes have been successfully synthesized as well and characterized by NMR spectroscopy and X-ray crystallography. All of the allylplatinum(II) complexes have exo/endo isomers.
In the S-NHC Pt complexes, the signals of backbone and NHC ligand which showed broad signals were observed in 1H NMR spectra. The exo-endo exchange cross peaks of the allylic group were also observed in 2D NMR spectra. But in the SO-NHC Pt complexes, the signals of backbone and NHC ligand were sharp and rigid in 1H NMR spectra. And there was no exchange cross peak observed in 2D NMR spectra. A rapid exo-endo exchange cross peaks of the allylic group was observed via sulfur inversion mechanism. The energy barriers was also examined by variable-temperature NMR techniques to give the ΔG‡ in the range of 15-16 kcal/mol.
Treatment of S-NHC Pt complex, 1a, with 50 equivalent pyridines cannot decoordinate the S atom on S-NHC ligand, but treatment of SO-NHC Pt complex, 2b, with only 5 equivalent pyridine can decoordinate the S atom on SO-NHC ligand. However, both these two complexes reacted with PPh3 to give the PPh3 substituted complexes. The better hemilability in SO-NHC than in S-NHC ligand is confirmed here.

並列關鍵字

isomerization ； thioether ； sulfoxide ； hemilability

參考文獻

1. Fischer, E. O.; Maasbol, A. Angew. Chem., Int. Ed. 1964, 3, 580-581.

2. Schrock, R. R.; Fellmann, J. D. J. Am. Chem. Soc. 1978, 100, 3359-3370.

3. Lee, H. M.; Lee, C. C. Curr. Org. Chem. 2007, 11, 1491-1524.

4. Bierenstiel, M.; Cross, E. D. Coord. Chem. Rev. 2011, 255, 574-590.

8. Scheele, U. J.; Dechert, S.; Meyer, F. Eur. J. Inorg. Chem. 2008, 14, 5112-5115.