Lack of electronic coupling despite half-wave potential splittings in ferrocenylvinyl-substituted [2.2]-paracyclophanes

Pseudo-para bis(ferrocenylvinyl)-[2.2]-paracyclophane 2 and its constitutional isomer 3 have been prepared and investigated with respect to their electrochemical and UV/Vis/NIR spectroelectrochemical properties. Cyclic and Square Wave voltammetric measurements show two consecutive one-electron oxidations with a modest redox splitting of 60 and 84 mV, respectively, for the individual Fc/Fc+ couples. In spite of the redox splitting, radical cations 2+ and 3+ constitute class I mixed-valent systems with no detectable electronic coupling between the individual redox sites. The results are thus very similar to those for the pseudo-ortho isomer 1+, which was previously reported (J. Organomet. Chem. 2012, 717, 14) but erroneously assigned the pseudo-para structure.