氮異環碳烯化合物分別對鋯金屬與硼錯合物之相關催化應用及探討

Abstract

最近幾年，氮異環碳烯咪唑與金屬錯合物的化學領域漸漸受到注目，而且也因為此類化合物對許多催化反應都具有活性，因此正快速的發展當中。 在一開始的研究中，順利的合成出一系列側邊臂上具有胺類基團的氮異環碳烯咪唑鹽類 2。接著，藉由加入NaN(TMS)2 可使咪唑鹽類 2 進行去氫化反應，進而得到咪唑化合物 3；其晶體結構中顯示咪唑與胺基會有相當特別的 N-H…C 分子間的交互作用形成。我們也製備Zr-NHC錯合物 4，利用咪唑化合物 3 與Zr(NMe2)4而得。這些Zr-NHC錯合物 4 也藉由X-ray單晶體繞射及NMR光譜加以確認。進一步，將錯合物 4 當做催化劑進行intramolecular hydroamination，催化結果顯示有不錯的活性。 接下來，我們朝向研究咪唑化合物 3與硼衍生物的反應特性；此類研究讓我們成功分離出錯合物 5。意外地，利用硼正離子化合物 5 與三氟甲烷磺酸銀進行反應，可以順利分離出一具有配位兩個不同化學環境的硼原子的咪唑化合物(6)。硼正離子化合物5 與化合物6可經由3中心2電子的B-H-B結構的四環中間體而進行互換。更進一步，我們合成一系列三烷基硼及三芳基硼做為前驅物進行Suzuki- Miyaura 耦合反應，實驗結果發現此類化合物具有不錯的活性。

The chemistry of Nitrogen-heterocyclic carbenes with metal complexes has experienced a rapid development due to their efficient for numerous applications in catalysis. In our onset study, a series of imidazolium salts for amino-linked Nitrogen -heterocyclic carbene ligands have been synthesized. Deprotonation of imidazolium salts 1 by NaN(TMS)2 to afford NHC free carbene compound 3, revealing an unexpectedly close intermolecular contact associated with the carbene and amine through an interaction, We also prepare Zr-NHC complexes 4 by treating of NHC carbene ligands (3) with Zr(NMe2)4. Those Zr-NHC complexes 4 were confirmed by single diffraction X-ray crystallography and NMR spectroscopy. We also carried out the hydroamination catalysis using Zr-complexes 4, showed good activity. Next, we investigate the NHC carbene ligand 3a with several of borane derivatives. These studies allowed us to isolate boronium complexe 5 upon the reaction of 3a-LiBr adduct with borane. Unexpected, treatment of the boronium complexes with silver triflate led to isolation of bis-borane compound 6 containing two chemically different boron species. The bis-borane and boronium complexes can interconvert via intermediate involved four-membered metallacycle of 3 centers, 2 electron of B-H-B motif through the assistance of pendant amine arm. Further, we synthesized trialkyl or triarylborane as precursors proceed to Suzuki-Miyaura Coupling with better condition in good yield.