Synthesis and NMR Characterization of Dinuclear Fe(II) Organometallic Complexes Containing a Nonequivalently Bridging 5-Aryl Tetrazolate Ligand

The synthetic routes to the formation of a wide range of dinuclear Fe(II) organometallic complexes of the general formula [Cp(CO)(L)Fe-N4C-C6H4-CN-Fe(L)(CO)Cp][SO3CF3], in which the 4-cyanophenyl-tetrazolate anion N4C-C6H4-CN acts as bridging ligand, are described. 1H and 13C NMR characterization of the product complexes indicate the presence of a significant interannular conjugation effect involving the aromatic rings of the organic spacer, the extent of which can be chemically modified by addition of electrophiles such as CH3+ and H+. Furthermore, the reversibility of protonation reaction entails the opportunity of modulating the conjugative properties of the title compounds by a proton addition-elimination mechanism.