A series of conformationally constrained 2,6-bisferrocenylphenyl thioethers were synthesized via Suzuki–Miyaura cross coupling reactions. Structural information was obtained using X-ray crystallography and dynamic 1H NMR spectroscopic studies, showing highly constrained m-terphenyl systems. Interaction of the ferrocene moieties through space mediated by the sulfur were studied by ultra-violet photoelectron spectroscopy (UPS), cyclic voltammetry, differential pulse voltammetry, UV–Vis–NIR spectroscopy and DFT computations. Electrochemical results show two, fully reversible 1e− redox processes for the ferrocenes where the separation of peaks is affected by both solvent and supporting electrolyte, suggesting significant electrostatic interaction which is further confirmed in the gas phase by UPS studies.Graphical abstractGeometrically constrained 2,6-diferrocenylphenylthioethers were synthesized and characterized. Through space interaction between the ferrocene moieties mediated by sulfur were evaluated by electrochemistry, photoelectron spectroscopy and UV–Vis–NIR spectroscopy of the mixed valence species. Enhanced interaction mediated by sulfur was ascribed to electrostatic interaction enhanced by the polarizability of sulfur.

A series of conformationally constrained 2,6-bisferrocenylphenyl thioethers were synthesized via Suzuki–Miyaura cross coupling reactions. Structural information was obtained using X-ray crystallography and dynamic 1H NMR spectroscopic studies, showing highly constrained m-terphenyl systems. Interaction of the ferrocene moieties through space mediated by the sulfur were studied by ultra-violet photoelectron spectroscopy (UPS), cyclic voltammetry, differential pulse voltammetry, UV–Vis–NIR spectroscopy and DFT computations. Electrochemical results show two, fully reversible 1e− redox processes for the ferrocenes where the separation of peaks is affected by both solvent and supporting electrolyte, suggesting significant electrostatic interaction which is further confirmed in the gas phase by UPS studies.Graphical abstractGeometrically constrained 2,6-diferrocenylphenylthioethers were synthesized and characterized. Through space interaction between the ferrocene moieties mediated by sulfur were evaluated by electrochemistry, photoelectron spectroscopy and UV–Vis–NIR spectroscopy of the mixed valence species. Enhanced interaction mediated by sulfur was ascribed to electrostatic interaction enhanced by the polarizability of sulfur.