Monodentate and bridging behavior of dinitriles ligands toward the fragment Cp(dppe)Fe+

The reaction of Cp(dppe)Fel with the dinitriles NC(CH2)(n)CN n = 3, 4, 6 in CH3OH and using NH4PF6 as halide abstractor afford the monodentate dinitrile complexes [Cp(dppe)Fe- (eta(1)-NC(CH2)(n)CN)PF6. Treatment of these mononuclear complexes with Cp(dppe)Fel afford the binuclear complexes [Cp(dppe)Fe-NC(CH2)(n)CN-Fe(dppe)Cp](PF6)(2). All the new products were characterized by elemental analysis as well as IR, H-1- P-31- and C-13-NMR spectroscopy and by UV-visible as well as cyclic voltammetry studies. The coordinative properties of nitriles were conveniently discussed using the C-13-NMR data and MO arguments, finding that the ligands behave mainly as sigma-donor. In the binuclear complexes the two Cp(dppe)Fe+ fragments are identical observing in the cyclic voltammogram only one oxidation wave. The high symmetry of the binuclear complexes is also corroborated by the spectroscopic results. Electrochemical results suggest no interaction between the metal centers.