Dimerisation of Fe bisdithiolene complexes: An electrochemical study

•Solution equilibrium between [Fe(L)2]22− dimers and [Fe(L)2]− monomers.•Role of the solvent interactions in the monomer/dimer equilibrium.•Stabilization of iron(III) bisdithiolene monomers by coordinating solvents.

An electrochemical study of the dimerisation of the [Fe(qdt)2]22− and [Fe(mnt)2]22− iron complexes in dichloromethane, dimethylformamide and acetonitrile, by cyclic voltammetry and ionic conductivity is reported. Ionic conductivity measurements indicate an increased dissociation of the dimers in dimethylformamide and acetonitrile compared to dichloromethane. In [Fe(mnt)2] in dichloromethane, only dimer oxidation processes are observed in cyclic voltammetry, while in [Fe(qdt)2] both dimeric and monomeric species are involved in redox processes. In acetonitrile and DMF the observed processes correspond to the dissociated monomeric species only. This study demonstrates the major role of the nature of the solvent in the monomer/dimer equilibrium in solution, which appears more easily shifted towards dissociation in the complex with qdt ligands than with mnt and is favoured by N- and O-containing solvents.

Graphical abstractAn electrochemical study demonstrates the major role of the nature of the solvent in the equilibrium between monomer and dimer of iron bisdithiolene complexes in solution.Figure optionsDownload full-size imageDownload as PowerPoint slide