Redox-Active 1D Coordination Polymers of Iron-Sulfur Clusters

Abstract

Here we describe the combination of an archetypal redox-active metal sulfide cluster, Fe₄S₄, with an organic linker, 1,4-benzenedithiolate, to prepare coordination polymers containing infinite chains of Fe₄S₄ clusters. The crystal structures of two solid materials have been solved from synchrotron X-ray powder diffraction data using simulated annealing and refined by a least-squares Rietveld refinement procedure. The electronic properties of these chains have also been characterized by UV-visible and Mössbauer spectroscopies. Additional experiments demonstrated that these chains can be solubilized by variation of the countercation and that the chain structure is maintained in solution. The redox-activity of the Fe₄S₄ clusters can be accessed with chemical reagents. Introduction of charge carriers by reduction of the Fe₄S₄ clusters is found to increase the electrical conductivity of the materials by up to 4 orders of magnitude. These results highlight the utility of Fe₄S₄ clusters as redox-active building blocks in preparing new classes of coordination polymers.