A DIIRON(III) COMPLEX CONTAINING N-N BRIDGES - SYNTHESIS, STRUCTURE, AND PROPERTIES

A dinuclear iron(III complex, Fe-2(salhn)(3) having three N-N linkages was synthesized using the tetradentate Schiff base ligand N,N'-bis(sa licylidene)hydrazine (H(2)salhn). The complex was characterized by ana lytical, spectroscopic and X-ray crystallographic techniques. It is re dox active and displays two one electron reductions corresponding to F e-2(III)/(FeFeII)-Fe-III and (FeFeII)-Fe-III/Fe-2(II) couples. A weal; antiferromagnetic spin-coupling is observed between the two high-spin Fe(III) centers due to superexchange via the N-N bridges. [GRAPHICS] ated (1-) and (3-) states confirm the MLCT formulation for the lowest excited states of the (2-) precursor complexes by showing typical low- spin Fe(III) signals of the oxidized species [(abpy)Fe(CN)(4)](-) and partially hyperfine-structured spectra for the reduced forms [(bpz)M(C N)(4)](3-). The latter are clearly tetracyanoiron(II) or -ruthenium(II ) complexes of the corresponding anion radical acceptor ligands and ar e thus isoelectronic with monoanionic tetracarbonylchromium(0) or -mol ybdenum(0) radical complexes.