Four-electron oxygen reduction by tetrathiafulvalene.

The four-electron reduction of oxygen by tetrathiafulvalene (TTF) in acidified 1,2-dichloroethane and at the acidified water/1,2-dichloroethane interface has been observed. Spectroscopy and ion transfer voltammetry results suggest that the reaction proceeds by the fast protonation of TTF followed by the 4-electron reduction of oxygen to form water. Electronic structure computations give evidence of the formation of a helical tetramer assembly ([TTF(4)H(2)](2+)) of two protonated TTF and two neutral TTF molecules. The protonated tetramer is potentially able to deliver the four electrons needed for the oxygen reduction. The production of water was corroborated by (1)H NMR analysis.