Electron interactions with Bis(penta-methylcyclopentadienyl) titanium(IV) dichloride and difluoride

We present a combined experimental and theoretical study of the interaction of electrons with Bis(penta-methylcyclopentadienyl) titanium(IV) dichloride (Cp*₂TiCl₂) and difluoride (Cp*₂TiF₂). The studied molecules are structurally similar to promising cancer chemotherapeutics and may be used in concomitant chemo-radiation therapy of cancer. Their distinct fragmentation behaviour, explored in the present study, could be used in evaluation of synergism induced by low energy electrons on DNA, similar to previous studies with cisplatin or other platinum compounds. We report the experimental measurements of partial cross sections for the dissociative electron attachment (DEA) and the electron ionization (EI) mass spectra of isolated molecules. Estimates of the absolute cross sections are done on the basis of cross-calibration in the case of DEA and on the basis of binary-encounter-Bethe calculation in the case of EI. EI of both molecules is similar, concerning cross section amplitude and fragmentation pattern. DEA is different: DEA to Cp*₂TiF₂ primarily results in the formation of stable parent anion, while DEA to Cp*₂TiCl₂ results in the strong fragmentation, primarily into Cl^- anion. The possible use of the molecules as the model species for studies of DEA efficiency in post-irradiation chemistry is also discussed