jp068994o_si_006.cif (9.35 kB)

Reversible Interchange of Charge-Transfer versus Electron-Transfer States in Organic Electron Transfer via Cross-Exchanges between Diamagnetic (Donor/Acceptor) Dyads

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posted on 21.06.2007 by Duoli Sun, Sergiy V. Rosokha, Jay K. Kochi
The choice of appropriate electron donors (D) and acceptors (A) allows for the first time the simultaneous observation of Mulliken charge-transfer states, [D,A], that can coexist in reversible equilibrium with electron-transfer states, {D+•,A-•}, for various diamagnetic organic redox dyads. The theoretical analysis based on the (two-state) Mulliken−Hush analysis of the intervalence optical transition, together with the spectral identification of the transient ion-radical pairs of D+• and A-•, leads to the construction of the unusual potential-energy surface consisting of a single minimum without any reorganizational barrier for electron-transfer cross-exchanges with driving forces close to the isergonic limit. The mechanistic implications of this direct demonstration of the facile charge-transfer/electron-transfer interchange are discussed.