銥鈀異核雙金屬錯合物的合成以及其催化活性的探討

Synthesis of an iridium-palladium bimetallic complex and its catalytic activity

楊竣皓(Chun-Hao Yang)

指導教授 ： 劉緒宗

國立臺灣大學/理學院/化學研究所/碩士(2021年)

https://doi.org/10.6342/NTU202103456

摘要

在本篇論文中以bppa [5-phenyl-2,8-di-(2-pyridinyl)anthyridine]作為配基，將銥金屬光催化單元和鈀金屬進行串聯成異核雙金屬錯合物Ir-F-Pd，並且透過離子置換後，可以順利取得其對應晶體，確定結構。該錯合物在催化反應的應用主要可以分為兩個部分，第一個部分為Suzuki 耦合反應，藍光照射的溫和條件下遂可進行。由控制實驗的反應速率比較，顯示有雙金屬效應。也意外發現加入額外的三級胺後，更可以提升該錯合物的反應活性，並且有良好的官能基耐受性。反應機制探討上，除了能量的轉移促使催化進行外，在有三級胺的狀況下，銥金屬中心扮演電子轉移的功用，幫助鈀金屬的還原，加速其反應。第二個部分則為無銅金屬參與的Sonogashira 耦合反應，該反應在相似的條件下可以順利進行。和單金屬錯合物催化活性的比較中，展現Ir-F-Pd有良好的產物選擇性，但是對於具有強推電子基團的芳香溴化物，反應則是無法進行，可能原因在文中討論。

關鍵字

異核雙金屬錯合物 ； 光催化 ； 鈴木耦合反應 ； 薗頭耦合反應

並列摘要

In this research, we used anthyridine-based ligand bppa serving as a linker and donors for iridium and palladium to form a bimetllic complex Ir-F-Pd. Its tetrafluoroborate salt crystallized in solution, which is suitable for crystallographic analysis to confirm the structural details. We had applied Ir-F-Pd as the photo-catalyst for two different reactions: Suzuki coupling and copper free Sonogashira coupling. In Suzuki coupling, we found that, with the illumination of visible light, coupling of aryl bromides with arylboronic acids can proceed at room temperature smoothly. By comparison of reaction rates, Ir-F-Pd shows a superior activity than the catalyst formed by a mixture of Ir-F and Pd-1. This catalytic system has a broad functional group tolerance. To our surprise, addition of tertiary amines in the system could improve the efficiency of catalysis. In term of mechanistic consideration, beside the energy transfer to assist the reaction, the iridium center could also undergo electron transfer process in the presence of tertiary amines to accelerate the reduction of palladium ions. In Sonogashira coupling, upon irradiation of visible light, Ir-F-Pd could promote the coupling of aryl bromides with arylacetylenes smoothly under mild conditions. This catalytic system shows a good product selectivity, not giving debromination side products, but the deactivated aryl bromides are not applicable in this system. A possible rationalization of this selectivity is discussed in the text.

並列關鍵字

heterobimetallic complex ； photocatalysis ； suzuki coupling ； sonogashira coupling

參考文獻

參考文獻

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