Entropy Changes and Electron Affinities from Gas-Phase Electron-Transfer Equilibria: A(-) + B = A + B(-)

Article abstract of DOI:10.1021/j100403a037

By measuring the electron-transfer equilibria 1, A(-) + B = A + B(-), at 150 deg C with a pulsed electron high-pressure mass spectrometer we determined the ΔG^o₁ values involving 12 new compounds.Measurements of the temperature dependence of K₁ for 21 reactions involving some of the new compounds and many compounds whose ΔG^o₁ had been determined previously led, via van't Hoff plots, to ΔH^o₁ and ΔS^o₁ values.These were interconnecting such that ΔH^o and ΔS^o continuous scales (ladders) were obtained.These were anchored to SO2 whose electron affinity is accurately known.Available geometries and vibrational frequencies for SO2 and SO2(-) permit the evaluation of S^o(SO2(-)) - S^o(SO2).Through the ΔS^o scale the S^o(B(-)) - S^o(B) for the other compounds B could be obtained also.Certain regularities in the S^o(B(-)) - S^o(B) data permitted entropy estimates to be made also for compounds for which no van't Hoff plots were made.In this manner a table of ΔH^o, ΔS^o, and ΔG^o data for the electron capture e + B = B(-) was obtained, which contains some 50 compounds B.Most of the compounds are substituted benzenes, quinones, conjugated acid anhydrides, and perfluorinated organics.