Theoretical studies on electronic structures and spectroscopic properties of [Ru(Htcterpy)X₃]^3- [X = NCS, CN, Cl]

The ground-structures of [Ru(Htcterpy)X₃]^3- [X = NCS (1), CN (2), Cl (3), tcterpy = 4, 4, 4″-tricarboxy-2, 2:6, 2″-terpyridine,] are optimized by DFT method (B3LYP). The calculated geometry parameters are in agreement with the experimental values. Absorption spectra in gas phase and in solutions (etha-nol and water) are predicted at the TD-DFT/B3LYP level. The solvent effects are seriously considered by u-sing the conductor-like polarizable continuum model (CPCM). For complexes 1-3, in gas phase and solution, the low-energy absorptions have a mixed MLCT/LLCT character, whereas the high-energy absorption are attributed to the intra-ligand π→π* charge transfer transitions. Our calculations reveal the blue-shift of the absorption spectra in solution with respect to those in gas phase, agreeing with experimental observations.