Atropisomeric 3,3′,4,4′,5,5′-Hexaferrocenyl-2,2′-bithiophene: Synthesis, Solid-State Structure, and Electrochemistry

3,3′,4,4′,5,5′-Hexaferrocenyl-2,2′-bithiophene (4) has been prepared using a straightforward synthesis protocol that follows the palladium-promoted Negishi cross-coupling of 2-Br-3,4,5-Fc3-cC4S (2) with 3,4,5-Fc3-2-ZnCl-cC4S (3) (Fc = Fe­(η5-C5H4)­(η5-C5H5)). The electronic and structural properties of 4 were investigated by UV–vis spectroscopy and single-crystal X-ray diffraction studies. Comparison of the appropriate bond distances in the 2,2′-bithiophene moiety shows electron delocalization. Cyclic and square-wave voltammetry and in situ UV–vis/NIR spectroelectrochemistry highlight the electrochemical properties of 4. The ferrocenyls in 4 can be reversibly and separately oxidized in dichloromethane and anisole solutions using [NnBu4]­[B­(C6F5)4] as supporting electrolyte. Generally, these studies prove electrostatic interactions among the ferrocenyl termini as oxidation progresses. The atropisomerism of 4 caused by the inner rotation barrier about the 2,2′-bithiophene bond was investigated by dynamic 1H NMR spectroscopy.