Solomon and co-workers have investigated the nature of the pre-edge features of the organotitanium complexes TiCl 4 , TiCpCl 3 and TiCp 2 Cl 2 , where Cp = (C 5 H 5 ) - denotes the cyclopentadiene anion, as models of antitumor agent titatanocene dichloride. As shown in Fig. (a), the titanium K-edge appears at 4980 eV although it is the pre-edge that is of primary interest, as it contains information about metal-ligand hybridization. A 1s → 3d pre-edge transition is obtained at 4976 eV using CAM-B3LYP/CIS, and the spectrum in Fig. is shifted by about 7 eV to match the experimental peak at 4969 eV. This transition is electric-dipole forbidden but quadrupole-allowed, and appears primarily due to the mixing of Ti(4p) and Ti(3d) orbitals. The pre-edge feature is most intense for TiCl 4 , with the intensity subsequently diminishing in TiCp 3 Cl and TiCp 2 Cl 2 .