Synthesis and NMR characterization of dinuclear Fe(II) organometallic complexes containing a non-equivalently 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.

Graphical abstractThe synthesis and the spectroscopic (IR; 1H and 13C NMR) characterization of a wide range of new dinuclear complexes of the type [Cp(CO)(L)Fe–N4C–C6H4–CN–Fe(L)(CO)Cp][SO3CF3] is reported. The interannular conjugation effect which is shown by the bridging [N4C–C6H4–CN]− ligand represents a promising feature for the incorporation of 5-aryltetrazole-based compounds on bi- or polymetallic arrays. Moreover, the extent of π-delocalization can be modified either in permanent way, by addition of CH3+, or reversibly by a proton addition–elimination mechanism.Figure optionsDownload full-size imageDownload as PowerPoint slide