A theoretical study of the structural and electronic properties of some titanocenes using DFT, TD-DFT, and QTAIM

Titanocenes are gradually proven to possess good anticancer activity. In this paper, we present a theoretical study of some properties of six promising anticancer titanocenes synthesized by the Tacke research group. The structural and electronic properties of the complexes have been investigated herein using the density functional theory (DFT) and the time-dependent DFT (TD-DFT) associated with a mixed basis sets comprising the 6-31 + G(d,p) basis set for C, H, and O atoms and the 6-31G(d) basis sets for the Ti4+ and Cl− ions. According to the results from topological analysis, even though there are strong Ti–C interactions in all complexes studied, the cyclopentadienyl derivatives are not covalently linked to the central Ti4+ ion through all of their carbon atoms. In addition, the Ti–Cl is the strongest metal-ligand bond. From the analyses of electronic spectra, it turns out that the complexes studied strongly absorb in the UV region of the electromagnetic spectrum and that the transitions are mainly LMCT, LLCT, and ILCT character. Our results are undoubtedly vital for further studies on the structure-activity relationship and mechanisms of interaction between the investigated titanocenes and DNA.