非血基質三價鈷超氧化物、過氧氫化物之合成、鑑定及反應性之研究

Abstract

本研究以修飾過後的新型配位基H2BDBP，合成出二價鈷錯合物CoII(BDBP) (1)，並參考實驗室王俊傑學長所開發的三價鈷錯合物CoIII(BDPP)(O2˙) 合成方式，合成出三價鈷超氧化物CoIII(BDBP)(O2˙) (2)。鑑定並比較兩者性質差異，發現同樣可以對較弱的氫氧鍵受質 TEMPOH進行奪氫反應，而得到CoIII(BDBP)(OOH) (3)。在超氧化物的質子化產物及其還原結果也有進行比較，兩者的質子化皆發生於配位基上，氫原子會再與超氧自由基團形成氫鍵。此外，與CoIII(BDPP)(O2˙) 最大的不同是錯合物2能夠對9,10-二氫蒽 (DHA) 的碳氫鍵進行活化而生成錯合物3，此活性可能是源自H2BDBP上甲苯基團的推電子，使得中心金屬的電子密度增加，提高反應性。最後，期望能藉由此研究，了解錯合物2對受質的碳氫鍵活化效果。A modified new ligand, H¬2BPBP, was prepared to synthesize a cobalt complex, CoII(BDBP) (1) ,which was further reacted with O2 to form a cobalt(III)-superoxo complex, CoIII(BDBP)(O2˙) (2), followed the synthetic method developed by Dr. Chun-Chieh Wang for CoIII(BDPP)(O2˙). Comparison of the two different cobalt(III)-superoxo complexes, after the characterization of 2 revealedthat both of them could form the cobalt(III)-hydroperoxo complexes CoIII(BDPP)(OOH) and CoIII(BDBP)(OOH) (3) via hydrogen atom abstraction from the TEMPOH substrate with the weak O-H bond. The protonation products of cobalt(III)-superoxo complexes and their reduction are also compared. Protonation was occurred on the ligand of both complexes, and hydrogen atom forms a hydrogen bond interaction with the superoxo moiety. Furthermore, unlike CoIII(BDPP)(O2˙), complex 2 will activate the C-H bond of 9,10-dihydroanthracene (DHA) to form complex 3. This result is probably due to the electron-donating ability of the benzyl groups on H2BDPP ligand to increase the electron density of the cobalt center and to enhance the reactivity of 2. Finally, through this study, it is expected that the effect of 2 on the activation of substrate carbon-hydrogen bonds can be understood.