Temperature dependence of ultra-exothermic charge recombinations.
We measured the temperature dependence (from +32 to -50 degrees C) of charge-recombination rates between contact radical ion pairs in isopropyl ether. In the systems selected for this study, aromatic hydrocarbon cations are the electron acceptors and the fumaronitrile anion is the electron donor. Nearly quantitative electron transfers occur at all temperatures. The charge recombinations have excess exothermicities of -60 kcal mol(-1) and exhibit a very weak temperature dependence. Our observations emphasize the absence of solvent effects and the relevance of nuclear tunneling in charge recombinations.
Serpa
Carlos
C
Department of Chemistry, University of Coimbra, 3000-535 Coimbra, Portugal. serpasoa@ci.uc.pt
Gomes
Paulo J S
PJ
Arnaut
Luis G
LG
de Melo
J Seixas
JS
Formosinho
Sebastião J
SJ