KINETIC ISOTOPE EFFECTS ON METAL TO NITROGEN PROTON TRANSFERS

The rate constants for proton transfer from the radical cation CpRu(PP h(3))(2)H-.+ to pyrrolidine and piperidine have been determined by der ivative cyclic voltammetry in CH3CN. The kinetic isotope effects k(H)/ k(D) at 20 degrees C are 2.7 for pyrrolidine and 2.3 for piperidine-su rprisingly small for transfers that are almost thermoneutral. The rate constant for proton transfer from CpW(CO)(3)H to aniline in CH3CN has been determined from the effect of the aniline concentration on the r ate of W --> W self-exchange; the kinetic isotope effect k(H)/k(D) at 25 degrees C is 4.2-surprisingly large for a transfer that is uphill b y 5.5 pk(a) units.