Vibrational Signatures of the Naked Aqua Complexes from Platinum(II) Anticancer Drugs

A computational and vibrational spectroscopic study of the aqua complexes obtained by hydrolysis of cis- and trans-diamminedichloroplatinum(II) is reported. Electrospray ionization has allowed cis- and trans-[PtCl(NH3)2(H2O)]+ species to be obtained as free ions in the gas phase where they were sampled by infrared multiple photon dissociation (IRMPD) spectroscopy in the NH/OH stretching frequency range (3200–3800 cm–1). The experimental features have been assigned by comparison with the linear IR spectra calculated for the optimized structures, revealing vibrational signatures characteristic of the two isomers.