Redox-Active, Dinuclear Sandwich Compounds [Cp*Fe(μ-L)FeCp*] (L = Naphthalene and Anthracene)

Although there has been much interest in the chemistry of bimetallic transition metal complexes, compounds with naphthalene or anthracene as bridging ligands are still rare. In this article, we describe the synthesis of the homodinuclear iron complexes [Cp*Fe(mu-eta 4:eta 4-L)FeCp*] (1: L = C10H8, 2: L = C14H10; Cp* = eta 5-C5Me5). The complexes were characterized by 1H and 13C{1H} NMR, UV/Vis, and 57Fe Mossbauer spectroscopy, and their molecular structures were determined by X-ray crystallography. Both complexes are diamagnetic as a result of the strong magnetic coupling of the 17e FeI centers mediated by the polyarene bridge. An analysisof the redox behavior of 1 and 2 by cyclic voltammetry andUV/Vis spectroelectrochemistry shows that the complexes can be oxidized reversibly in two well-separated one-electron steps to the monocation [Cp*Fe(mu-L)FeCp*]+ and the dication [Cp*Fe(mu-L)FeCp*]2+. The reduction to the monoanion [Cp*Fe(mu-L)FeCp*] was also observed.