The neighboring group effect of fluorine in the tritium labeling of organic substrates with [Cp*(PMe3)IrMe(CH2Cl2)]+[BArf]-, a cationic iridium(III) complex

The cationic Ir(III) complex, [Cp*(PMe3)IrMe(CH2Cl2)][BArf] (1, Cp* = eta(5)-C5Me5, BArf = MeB(C6F5)(3)), has been shown to be a useful reagent in the tritium and deuterium labeling of organic substrates. During a recent reaction of 1 with a fluorinated molecule, we observed an unusually high incorporation of tritium ortho to the aromatic fluorines. To probe whether this was an isolated incident or a more general phenomenon, we have investigated the application of 1 towards the tritiation of simple fluorinated organic substrates. Our results indicate that aromatic fluorine indeed does exhibit a neighboring group effect in terms of directing ortho H/T exchange. The directing influence appears to be at least as strong as the hydroxyl moiety reported in previous works. Copyright (c) 2006 John Wiley & Sons, Ltd.