Charged cyclophanes with extended conjugation: the effect of the cyclophane hub on the charge distribution

Abstract

Compounds 1, 2 and 3 were chemically reduced with lithium, sodium and potassium metals in [²H₈]THF at 220 K. In each case the reversibility of the process was tested by quenching with molecular oxygen. The reduction of 1 with all three metals yields the corresponding tetraanion salt 1^4–/4M⁺. Compound 2 was reduced reversibly with potassium and sodium only, while compound 3 underwent decomposition. According to the UV–VIS spectra and the electrochemical results, the tetraanion species is formed via a stepwise four-electron transfer process. A strong effect of the cyclophane hub on the charge distribution visàvis a relevant model system is demonstrated.