摘要 : The stoichiometry and stability of a series of zinc(II) complexes of bis(1,4,7-triazacyclononane) ligands containing from two- to eight-membered polymethylene bridging chains have been studied by pH potentiometry. Equilibrium mode... 展开 The stoichiometry and stability of a series of zinc(II) complexes of bis(1,4,7-triazacyclononane) ligands containing from two- to eight-membered polymethylene bridging chains have been studied by pH potentiometry. Equilibrium modeling of the data indicates that stable 1:1 complexes form when the linker group contains only two or three C atoms. Ligands comprising longer bridging chains form stable 1:1 and 2:1 Zn(II)-L complexes. The stability trends observed for the 1:1 complexes follow those of the Cu(II) complexes where the ligands with the shorter bridging groups form the most stable 1:1 complexes. The 2:1 complexes show virtually no variation in stability throughout the series. The X-ray structures of two monomeric complexes, [Zn(EM2)][ZnCl3ONO2] (1) and [Zn(EM3)][ZnBr4] (2), and a dimeric complex, [Zn-2(EM5)(mu-Cl)(3)](2)(ClO4)(2).4H(2)O (3), containing a face shared bioctahedral Zn(mu-Cl)(3)Zn cluster are determined. The structure of the [ZnCl3ONO2](2-) anion has not previously been reported. (C) 2000 Elsevier Science S.A. All rights reserved. [References: 24] 收起