Azo‐Cyanamide Bridged Dinuclear Iron Complexes Exhibiting no Electronic Coupling but Moderate Magnetic Coupling between the two Iron Centers

Abstract To investigate the effect of long‐distance organic ligand on electronic coupling between metallic atoms, the mononuclear and dinuclear complexes [Cp(dppe)Fe(apc)] ( 1 ), [{Cp(dppe)Fe} 2 (μ‐adpc)] ( 2 ), [{CpMe 5 (dppe)Fe} 2 (μ‐adpc) ( 3 ) and their oxidized complexes [Cp(dppe)Fe(apc)][PF 6 ] ( 1[PF 6 ]), [{Cp(dppe)Fe} 2 (μ‐adpc)][PF 6 ] ( 2[PF 6 ] 2 ), [{CpMe 5 (dppe)Fe} 2 (μ‐adpc)][PF 6 ] 2 ( 3[PF 6 ] 2 ) (Cp=1,3‐cyclopentadiene, CpMe 5 =1,2,3,4,5‐pentamethylcyclopentadiene, dppe=1,2‐bis(diphenylphosphino)ethane), apc − =4‐azo(phenylcyanamido)benzene and adpc 2− =4,4′‐azodi(phenylcyanamido)) were synthesized and characterized by cyclic voltammetry, UV‐vis, single‐crystal X‐ray diffraction and Mössbauer spectra. Electrochemical measurements showed no electronic coupling between the two terminal Fe units, However, the investigation results of the magnetic properties of the two‐electron oxidized complexes indicate the presence of moderate antiferromagnetic coupling across 18 Å distance.