(16) With I and I1 the analogous experiment shows enrichment at one of the two p2 oxygens as well as at the terminal oxygens. Recall that the water exchange experiments' also indicated a second site of exchange on these reduced anions. Synthesis [Fenselau, AH; Moffatt, JGJ Am. Chem. SOC. 1966, 88, 17621 of" 0-enriched Me, SO (60= 15 ppm) yielded a product that contained an impurity (So= 320 ppm) that we have been unable to identify. ...