多胺與多乙酸基配位子與金屬離子錯合物穩定常數研究

Abstract

中文摘要 利用滴定的方式求得配位子的 質子化常數及配位子與金屬離子錯合物的穩定常數,這些常數值在論文中 被討論;而所研究的配位子可以分為下列三大類:(一)線形四胺基與線形四 胺二乙基配位子(二)線形五胺基與線形五胺二甲基配位子(三)大環四胺多 乙酸基配位子 研究配位子的末端氮原子接上取代基對線形四胺基與線 形五胺基配位子,末端氮原子的質子化常數與配位子的總鹼性度的影響發 現,取代基使配位子的第一與第二質子化常數值及配位子的總鹼性度增高; 在配位子與金屬離子錯合物中,因為立體效應,取代基相互排斥的結果,反 而降低金屬離子錯合物的穩定性;但在線形五胺二甲基配位子與銅離子錯 合物中,因各配位子與銅金屬離子錯合物結構有所不同,降低了立體效應的 影響程度,使配位子的總鹼性度越高金屬離子也越穩定. 在大環四胺二 乙酸基配位子中,第一與第二質子化位置有兩種可能的質子化過程,一種為 先質子化在二級胺,另一種為質子化在三級胺上.研究也証實了大環四胺多 乙酸基配位子與金屬離子錯合物的穩定常數大小隨著配位子的總鹼性度, 所帶的負電荷,具有的配位原子數的增加而增高.同時也發現大環四胺二乙 酸基配位子對金屬離子形成錯合物的反應中,反應平衡所需時間長,特別是 與鑭系稀土離子的反應平衡時間常需要一至數日. Abstract Ligand protonation constants, the stability constants of the transition metal ions and lanthanide ions complexes were determined by the potentionmetric pH titration method. There are two kinds of ligand were studied in this thesis. one is linear polyamine[3,6,9,12-tetraazatetradecane(222-tet-Et2); 3,6,10,13- tetraazapentadecane(232-tet-Et2); 3,7,10,14-tetraazahexadecane(323-tet-Et2)],another is macrocyclic polyamino carboxylates[DO2A(1,4,7,10- tetraazacyclodode-cane-1,7-diacetic acid)] The study of the the terminal nitrogen atom of linear polyamine,[232-tet-R, 323-tet- R, 222-tet-R,(R=Me2, Et2) which has a substituent is more basic than the other polyamine which has not a substituent on terminal amine. The stabiliry of complexes formed by linear polyamino lig,nd with metal ions. While terminal amine of ligand, which has substituent forms complexes with transition metal ions, its stability constants is lower than those the unsubstituented ones. The difference is contrituted from steric effect of complexes by substi-tuent interaction. Two types of trends of the first and second protonational processing of the DO2A are observed. One type is that protons protonate on two secondar amines of ligand, another type is that protons protonate on two tertiary amines ofligand. The stability constants of metal ions complexes of macrocyclic polyamino polycarboxylates increase with increasing charge density, overall basicity, and number of donor atoms of ligands. We also found that the reaction of DO2A with metal ions, a long time equilibrium time is needed, especially for DO2A reacting with lanthanide ions.