雙核銅金屬錯合物之合成與催化探討

Abstract

本論文內容主要合成多牙氮配體2,7-bis(3,5-di-R-pyrazol-1-yl)-1,8-naphthyridine (4a, R=H ; 4b, R=CH3)及其二價雙銅金屬錯合物[(4x)(μ-OH)(μ-CF3CO2)Cu2(CF3CO2)2] (5a, x=a ; 5b, x=b)，藉X-ray單晶繞射及ESI-MASS質譜分析鑑定結構，雙銅中心均為五配位雙三角錐幾何構型，由三氟醋酸根與羥基組成架橋基聯結兩金屬核。 於氧氣中，錯合物5a在催化苯胺氧化偶合製備偶氮苯化合物上展現極高效率，鹵素取代苯胺亦可順利進行反應，由動力學實驗得知雙銅金屬催化劑於反應速率表現上較單核銅催化劑優秀，此外不對稱偶氮苯化合物也可藉此催化反應獲得。 以tBuOOH為氧化劑，5a可以催化甲醇和胺類進行胺類甲醯化反應，過渡金屬催化，直接由醇類與胺類進行反應，產生醯胺化合物及一分子氫氣是近年來興起的概念，有效減少強酸強鹼的使用，尤其由銅金屬做為催化劑的例子並不常見。

We have successfully prepared 2,7-bis(3,5-di-R-pyrazol-1-yl)-1,8-naphthyridine (4a, R=H ; 4b, R=CH3), which is a multidentate dinucleating ligand. Coordination of 4x (x = a~b) with copper precursor resulted in the formation of dinuclear copper complex [(4x)(μ-OH)(μ-CF3CO2)Cu2(CF3CO2)2] (5a, x=a ; 5b, x=b). 5a was characterized by X-ray diffraction and ESI-MASS. The coordination geometry about each Cu(II) is approximately a trigonal-bipryamidal. The two metal ions are linked by bridging carboxylate group and hydroxyl group. We reported an oxidation of aromatic anilines to aromatic azo compounds catalyzed by 5a using O2 as the oxidant. Importantly, unsymmetrically substituted azobenzenes can be constructed by using this oxidative method. Direct formation of amides from alcohols with amines has recently received attention from the viewpoint of the development of environmentally benign processes. 5a was found to be a catalyst for the direct N-formylation of amine with MeOH using tert-butyl hydroperoxide (tBuOOH) as the oxidant.