Azo-Cyanamide bridged dinuclear iron complexes exhibiting no electronic coupling but moderate magnetic coupling between the two iron centers

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(mu-adpc)] (2), [{CpMe5(dppe)Fe}2(mu-adpc) (3) and their oxidized complexes [Cp(dppe)Fe(apc)][PF6] (1[PF6]), [{Cp(dppe)Fe}2(mu-adpc)][PF6] (2[PF6]2), [{CpMe5(dppe)Fe}2(mu-adpc)][PF6]2 (3[PF6]2) (Cp=1,3-cyclopentadiene, CpMe5=1,2,3,4,5-pentamethylcyclopentadiene, dppe=1,2-bis(diphenylphosphino)ethane), apc-=4-azo(phenylcyanamido)benzene and adpc2-=4,4 '-azodi(phenylcyanamido)) were synthesized and characterized by cyclic voltammetry, UV-vis, single-crystal X-ray diffraction and Mossbauer 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 angstrom distance. A series of novel azo-cyanamide bridging iron complexes have been synthesized and characterized. The distance between the metal irons at the ends of the complexes reaches 18 angstrom, and there is no electronic coupling between the metal irons, but there is moderate antiferromagnetic coupling. image