Counterion-dependent deuteration of pentamethylcyclopentadiene in water-soluble cationic Rh(III) complexes assisted by PTA

[Cp*RhCl(PTA)2]X (PTA = 7-phospha-1,3,5-triazaadamantane) undergoes an H/D exchange process between the methyl groups of Cp* and D2O whose rate depends on the coordinating ability of the counterion X-. Kinetic studies and DFT calculations indicate that deuteration involves the abstraction of a Me-Cp* proton by a coordinated OH-; the formation of the latter seems to be facilitated by the presence of the N-basic centers of PTA.