Formation of high-energy phosphate bonds effected by electron-deficient sulfides

Reactions of cation radicals of EE systems. 9. Kinetics and mechanism of the reaction of thianthrene cation radical with nitrate ion

“…In this medium, too, the reaction rate is independent of Th (series 4-6) and ThO (series 4, 6, and 7) concentrations. The striking feature of these data is the 20.0 (±2.0) 30.4…”

“…The enthalpic and entropic data can be coherently interpreted by assuming that, for all the substances examined, except for urea, in the concentration process water molecules are released from the cosphere of the solute to the less structured state of bulk water. 14,16,20 On the contrary, from the distorted and less ordered " Units: J mol'1 (kg"1 mol'1). b All data have been recalculated in the present work, except for those of ref 14 and 16. cosphere of urea,21 water molecules will release to the more structured bulk state.…”

“…This is interpreted as a proof for the existence of an overlapping process among the hydrophobic hydration cospheres favoring a large release of water. 14,16,20 According to Rowlinson and Franks,1 this behavior is peculiar to aqueous solutions containing hydrophobic solutes. On the contrary, the relation |TASE| < |AHe| is peculiar to polar solutes in water.…”

“…Reactions of the cation radical of thianthrene, a sulfur-centered EE system,2 with a broad spectrum of nucleophiles and reducing agents have been studied,10'3™16 as have similar reactions involving phenoxathiin,12,14'15,17 phenothiazine,5,18 and substituted phenothiazines.10,10, 19 The cation radical of thianthrene is also known to initiate cationic polymerizations3 as well as to play a significant mechanistic role in models for oxidative phosphorylation. 20 Although both disproportionation and half-regeneration have been argued to be the dominant mechanism for reactions of these EE systems with nucleophiles,2 a consistent observation is the re-formation of cation radical precursor in the amount of 50% of the cation radical consumed en route to formation of the addition (or substitution) product.…”