Kinetic studies of electron-transfers between the mono- and dinegative ions of anthracene and 1,1-diphenyl ethylene

Abstract

Following the previously described study of the reaction of sodium anthracene, A., with 1,1- diphenyl ethylene, D, giving the sodium salt of the dimeric dianion, -C(Ph) 2 • CH 2 . CH 2 C(Ph) - 2 , nameIy 2A−. + 2D → 2A + − DD − we investigated now the reaction of disodium anthracene, A 2~ with D. It was shown that this extremely fast process produces a mixed dimer ~AD~, which decomposes reversibly into J7 The virtually irreversible dimerization of D7 into ~DD~ leads to complete decomposition of ~AD~ into AT* + ~DD~. The kinetic studies of these processes allowed us to evaluate the relevant rate and equilibrium constants and forced us to reconsider the results of the previous study. The previously proposed mechanism of conversion of A~ + D into A + ~DD~ was found to be correct, namely A* +D A+D* (rapid equilibrium), (i) D ^+ D --> DD• (rate determining step), (2) ~DD- + A~ --> ~DD~ (rapid electron transfer). (3) In addition, side reactions, A^ + A A 2~ + A, (4) A 2~ + D ~AD~, (5) -A D - *± A^+DT (6) form a small amount of the transient mixed dimer ~AD~. This transient was erroneously identified in the previous study as the monomeric radical-ion, and this mistake led to incorrect values of K l9 k2 and I£dig8>> DD~ 2D~, ...(I£di8s.). The corrected results derived from the present studies are K x « 10~7, k2 = 800 1. mole-1 s-1, Jfdi8S> « 10~15 mole/1. The scheme was proved to be self-consistent, and the value K x was confirmed by the potentiometric and equilibrium data.