摘要 : The Ni(II) complexes of a series of bis(1,4,7-triazacyclonon-1-yl)alkanes with polymethylene bridges containing two to six C atoms (EMn (n = 2-6)) have been studied by pH potentiometric, electrochemical, UV-Vis spectrophotometric,... 展开 The Ni(II) complexes of a series of bis(1,4,7-triazacyclonon-1-yl)alkanes with polymethylene bridges containing two to six C atoms (EMn (n = 2-6)) have been studied by pH potentiometric, electrochemical, UV-Vis spectrophotometric, and X-ray crystallographic experiments. Ligands with bridges of two or three C atoms (EM2 and EM3) exclusively form mononuclear complexes and those with longer linker chains form binuclear dimers. The X-ray structures of [Ni-2(EM5)(2)]Cl3NO3.15H(2)O (3) and [Ni-2(EM6)(2)]Cl-3(NO3)(2).6H(2)O (4) establish the existence of the dimeric complexes in which two Ni(II) ions are sandwiched between two ligands. The structure of [NiEM3](ClO4)(2).NaClO4.H2O (1) is monomeric with a distorted NiN6 coordination. Equilibrium models of pH potentiometric data from batch titrations of equimolar Ni(II) ligand aqueous solutions provide a rationale for the formation of the various complex species. Electrochemical cyclic and square wave voltammetric and UV-Vis continuous variation experiments on the series of Ni(II) complexes are also reported and interpreted based on the equilibrium models. (C) 2002 Published by Elsevier Science B.V. [References: 37] 收起