因應酵素的雙核金屬活性中心的發現,化學家們發展雙金屬結構,期望以仿生結構進行多樣性的催化探討。 本篇論文利用2-(pyrazol-1-yl)-7-(2-pyridyl)-1,8-naphthyridine (ppnp)作為四牙配基,合成單核與雙核錯合物,更以單晶成功鑑定雙釕diRu與雙鎳diNi錯合物結構。晶體結構顯示ppnp與金屬配位並形成兩組金屬五元環;diRu結構中,雙釕以金屬鍵連接,並以三個醋酸根與雙釕金屬配位,使金屬中心均為六配位;diNi中以兩個OH橋基連結兩個鎳金屬,其中一個OH更以μ3-OH的形式連結另一個單元,形成二聚體,亦同時使鎳金屬均為六配位。 硼氫化鈉本身還原酯類的效率並不高,但在雙鎳金屬錯合物diNi幫助下,可有效提升硼氫化鈉還原酯類的能力,以不錯的產率得到相應的醇類。動力學實驗亦證實雙核的表現優於單核金屬催化劑。
The discovery of bimetallic centers in enzymes makes chemists research the structure which can accommodate two metal ions simultaneously in order to mimic the activity of enzymes. In this work, we have successively synthesized mono-, bi-metallic complexes using 2-(pyrazol-1-yl)-7-(2-pyridyl)-1,8-naphthyridine (ppnp) as multidentate. Among them, the structures of diRu and diNi can be confirmed with single crystals. The crystal structures both showed that ppnp coordinated with two metals to form two five-member rings. In diRu, two ruthenium ions linked by Ru-Ru double bond and three acetates to afford octahedral structure around each ruthenium ion. In diNi, two OH as bridging units connected two nickel ions in each ppnp, and one of them linked another unit in μ3-fashion to form the dimer which makes all nickel ions octahedral structure. NaBH4 cannot reduce esters efficiently, but the reducing ability can be improved a lot in the assistance of diNi as catalyst to get the corresponding alcohols in good yield. The dynamic experiment also proved that bimetallic catalyst is better than monometallic one.