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 D(2)O 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.