LAUSR

Abstract In this paper we report the preparation, characterization (infrared absorption spectroscopy, photoluminescence, and thermogravimetric analysis), and DFT based electronic structure calculations (GKS-EDA), used to shed light into the metal-ligand bonding situation, of a set of Eu 3+ complexes containing tris-(pyrazolyl)borate “scorpionate” (Tp) and phenantroline (phen) as ligands in different proportions. The Infrared results point out that the complexes [Eu(phen)(Tp) 3 ] (Eu/phen/Tp molar ratio 1:1:3) is not obtained, suggesting that Tp ligand displaces phen ligand leading to the formation of [Eu(Tp) 3 ] (molar ratio 1:3). Photoluminescence results, including emission and excitation spectra give support to the vibrational spectra interpretation, confirming that three ligands Tp displace the ligand phen, to form [Eu(Tp) 3 ]. GKS-EDA results show that Eu 3+ ---Tp interactions are much more stabilizing than Eu 3+ ---phen interactions, in agreement with the experimental evidences that the third Tp remove phen from the Eu 3+ coordination environment.