Sample Exercise
Which of the following complexes of Ti3+ exhibits the shortest wavelength absorption in the visible spectrum: [Ti(H2O)6]3+;[Ti(en)3]3+; [TiCl6]3-?
SOLUTION The wavelength of the absorption is determined by the magnitude of the splitting between the d-orbital energies in the field
of the surrounding ligands. The larger the splitting, the shorter the wavelength of the absorption corresponding to the transition of the electron from the lower-to the higher-energy orbital. The splitting will be largest for ethylenediamine, en, the ligand that is highest in the spectrochemical series. Thus, the complex with the shortest wavelength absorption is [Ti(en)3]3+