萘啶-吡唑配基之釕金屬錯合物合成與氫轉移反應的催化應用探討

本論文主要探討以萘啶-吡唑為主要骨架，並在萘啶七號位上修飾不同官能基(包含胺基、醯胺基和甲基)之配位基，與[Ru(η6-p-cymene)Cl2]2反應合成出不同的單核釕金屬錯合物(6 - 8)。使用核磁共振光譜、質譜儀及X光單晶繞射分析晶體結構，顯示釕金屬中心有芳香環(p-cymene)及萘啶-吡唑的配位，且外圍有一氯離子的陽離子型錯合物，而萘啶上七號位的官能基並未配位至釕金屬中心。本篇以甲酸及甲酸鈉作為氫的來源，在釕金屬催化劑的幫助下進行乙醯丙酸的氫轉移反應，並脫水得到γ-內戊酯產物。在適當的甲酸/甲酸鈉比例下，錯合物6可在甲苯中有良好的反應活性，由於甲酸鈉並無法完全溶在甲苯溶劑中，故在此條件中加入少量的水後，可以發現反應性有大幅度的上升，也因此針對水的效應做了討論。比較不同釕金屬錯合物在催化活性上的差異時，可以觀察到本篇合成出帶有胺基或醯胺基(6 和 7)的單釕錯合物，對於此氫轉移反應有顯著幫助，此一現象顯示出配基所提供的氫鍵效應能夠促進此氫轉移反應的進行。

關鍵字

萘啶配位基；釕金屬錯合物；氫轉移反應；金屬-配基偕同效應

並列摘要

In this work, we have synthesized naphthyridine-pyrazole based ligands with three different functional groups (including amino, amide, and methyl) at 7-position of naphthyridine. These ligands react with [Ru(η6-p-cymene)Cl2]2 to form the corresponding mono-nuclear Ru(II) species (6 - 8). Structural characterizations are performed successfully by NMR, MS and X-ray crystals. Notably, analysis shows the functional groups (amino and amide) on ligand backbone are not in chelation mode to the Ru(II) center. Catalytic application of ruthenium complexes on transfer hydrogenation of levulinic acid to γ-valerolactone was studied. Under suitable amount of formic acid/sodium formate as the hydrogen source, complex 6 shows good performance in toluene. Due to the poor solubility of sodium formate in toluene, the presence of some water in reaction medium leads to a dramatic increase in activity. As a result, the effect of water is discussed. Comparison among different ruthenium complexes displays a distinct reactivity difference. Especially excellent performances are found in the Ru(II) catalysts bearing amino or amide groups(6 and 7). This phenomenon indicates the ligand assisted transfer hydrogenation via possible hydrogen bonding interaction.