• 作者： 鍾崇燊
• 作者服務機構： 國立清華大學化學系
• 中文摘要： 鏈狀配位金屬錯化合物中，不對稱氮中心之反轉反應，利用鹼來催化，使氮原子上之質子失去後，才進行氮中心之構造反轉，此為一自由鹼之催化反應機構，而在四胺基巨環配位銅錯化合物中，不對稱氮中心之反轉，可被酸或鹼催化。在強酸中，利用酸催化，切斷銅一氮之配位鍵，而進行氮中心之反轉。在弱酸或鹼性溶液中，可利用鹼來催化。若配位鹼有另一對未配位之電子，而能靠近到鄰近氮原子上之氫原子，形成配位環狀之中間體，則其反應速率比自由鹼來得快。因此，提出分子內氫鍵之形成，氮原子反轉及環構造改變為同時發生之一步協合反應機構。
• 英文摘要： The inversions at asymmetric nitrogen centers of open-chain ligand complexes of metal ions arecatalyzed by base. The configurational inversions at nitrogen centers are expected only after deprotona-tion. A free base-catalyzed mechanism was proposed for these reactions. The inversions at asymmetricnitrogen centers in tetraamine macrocyclic ligand complexes of copper (II) are catalyzed by base as wellas by acid. In strongly acidic media, the reaction is acid catalyzed due to the required cleavage of thecopper-nitrogen bond. In basic or slightly acidic media, the inversions at asymmetric nitrogen centers arebase catalyzed. The kinetics shows a strong preference for the reaction of coordinated bases which containanother lone pair in the vicinity of the amine hydrogen over free bases. The hydrogen is partially removedfrom the nitrogen in the activated complex. A concerted mechanism is proposed in which intramolecularhydrogen bonding, nitrogen inversion, and ring conformation changes occur.
• 中文關鍵字： --
• 英文關鍵字： --