Electronic structure, Raman and infrared spectra, and vibrational assignment of carboplatin. Density functional theory studies

The molecular structure, vibrational frequencies, infrared intensities and Raman scattering activities of carboplatin were calculated by the modified mPW1PW91 (mPW) density functional model using several basis sets. The results from natural bond orbital (NBO) analysis have provided new insights into platinum–ligand bonding, the hybridization of atoms and the electronic structure of the title molecule. The FT-Raman and FT-infrared spectra have been measured for carboplatin in the solid state. The theoretical Raman spectrum predicted by the mPW method shows very good agreement with experiment. In particular, the frequencies and Raman intensities of the platinum–ligand vibrations are very well predicted at the mPW/LanL2DZ level of theory. The detailed interpretation of the vibrational spectra has been made on the basis of the calculated potential energy distribution, PED. The characteristic ‘marker’ bands of carboplatin are discussed. The reported vibrational assignment can be used for further spectroscopic studies of new anticancer drugs, which are structurally similar to carboplatin. q 2006 Elsevier B.V. All rights reserved.