| The probability of reaction within the solvent cage is determined by the relative rates of diffusional escape (k;1,10-Dibromodecane exhibited essentially no cage effect (z = 0.01), while iodoform yielded a very large value of z (4.4). The normal chain alkyl diiodides of the form I-(CH;The cage effect thus determined was independently confirmed by allowing a monoiodide and a diiodide to compete for tributyltin hydride. In addition, the cage effect determined from reported absolute rates for iodine transfer compared favorably with our values, in the case of the normal chain alkyl diiodides.;The very small differences in cage effect among different diiodides can be rationalized as arising out of similar values of absolute rate constant for iodine transfer. The other explanation is that the most probable end-to-end separation is not significantly different for the several diiodides investigated. Alternatively, a small increase in end-to-end distance for longer alkyl chains is compensated by a decrease in k;The studies performed in benzene and hexane excluded hydrophobic interaction between the reagents as a reason for similar z values. Additional experiments conducted did not rule out intramolecular radical-iodine complexation in the monoiodo alkyl radical (I-R... |
