New route to bimetallic imidazolate-bridged complexes. III. Solution properties of dinuclear copper and nickel complexes and their mononuclear precursors

Abstract

Solution study of the dinuclear imidazolate- bridged complexes shows that the dimeric structure is retained even in good coordinating solvents such as pyridine, DMSO or imidazole. The mononuclear nickel complex which is diamagnetic in the solid state and in non-coordinating solvents becomes fully paramagnetic in the presence of an excess of pyridine. Its homodinuclear homologue displays a rather different behaviour for addition of pyridine gives rise to a limited paramagnetism seemingly corresponding to one nickel ion on two becoming high-spin. A similar behaviour characterizes the heterodinuclear complex. EPR spectra of the dicopper complexes emphasize the importance of dipolar interactions in the solid state and in non-coordinating solvents. However they are removed by good donor solvents.