桥联异多核配合物稳定性的ESR研究

ESR Studies on the Stability of Imidazolate and r,r'-Bipyridinate Bridged Heteropolynuclear Complexes

用电子自旋共振方法研究了咪唑和T,T^1-联吡啶桥联配合物的稳定性。结果表明,咪唑桥联异双核和异三核配合物中的咪唑桥均在pH=7.8～8.5范围内断裂,形成单核配合物[(NH_3)_5CoIm]^(2+)和[(dien)CuH_2O]^(2+),而T,T^1-联吡啶桥联的异双核配合物的联吡啶桥则在pH<6.0时才开始断裂,形成单核配合物。当pH=3.7～2.5时,[(dien)CuH_2O]^(2+)经水合反应,形成[Cu(H_2O)_6]^(2+)。

The determination of the pH dependent ESR spectra of some imidazolate and r,r' -bipyridi-nate bridged heteropolynuclear complexes:Co-Im-Cu, Co-Im-Cu-Im-Co and Co-(r,r' -bpy)-Cu have been carried out and show that the imidazolate bridged dinuclear and trinuclear cations exist as major species in .the solution only between pH: 7. 8-8. 5,but r,r' -bipyridinate bridged cation exists in solution in a wider pH range (pH>6). At low pH the imidazolate and r,r' -bipyridinate bridge are broken and eventually free Cu2+ion forms.