Metal Complexes with Macrocyclic Ligands. Part XXXI. Protonation studies and complexation properties of tetraazamacrocyclic methylenephosphonates with earth-alkali ions
作者:Rita Delgado、Liselotte C. Siegfried、Thomas A. Kaden
DOI:10.1002/hlca.19900730115
日期:1990.1.31
importance, as the above ligands can form complexes with alkali-metal ions. The potentiometric results for the earth-alkali ions show that beside mononuclear complexes of different degrees of protonation ([MLHn], n = 0–4), also binuclear species are formed ([M2LHm], m = 0–2). It is interesting that 1 with the smallest macrocyclic ring has the greatest tendency to form binuclear complexes, which are so stable
三个配体1,4,7,10-四氮杂环十二烷-1,4,7,10-四(亚甲基膦酸)(1),1,4,7,11-四氮杂环十三烷-1,4,7,11-四(通过将相应的大环与甲醛和亚磷酸缩合,合成了亚甲基膦酸(2)和1,4,8,11-四氮杂环十四烷-1,4,8,1 1-四(亚甲基膦酸)(3)。已经通过电位滴定法在25°和I = 0.1 M(Me 4)N(NO 3)下测定了与碱土金属离子的质子化和稳定性常数。由于前两个质子化常数较高,所以1H-NMR测量对于确定它们是必需的。在不同的支持电解质(NaNO 3,KNO 3,RbNO 3,CsNO 3和Me 4 N(NO 3))中滴定表明,它们的选择至关重要,因为上述配体可以与碱金属离子形成络合物。碱土金属离子的电位分析结果表明,除了不同质子化程度的单核络合物([MLH n ],n = 0–4)之外,还形成了双核物质([M 2 LH m ],m = 0–2 )。