Predicting inversion of MO energy levels by DFT calculations in tricarbonylpolypyridylrhenium(I) complexes

CATTANEO, MAURICIO; FAGALDE, FLORENCIA; KATZ, NÉSTOR E.

Córdoba

Congreso; XVII Congreso Argentino de Fisicoquímica y Química Inorgánica; 2011

AAIFQ

DFT calculations have recently emerged as powerful tools for predicting molecular properties and reactivity in coordination compounds. In particular, MO calculations of ground and excited states of several tricarbonylpolypyridylrhenium(I) complexes have led to theoretical UV-visible spectra in good agreement with experimental results.[1] We have already reported the syntheses and physicochemical properties of a series of compounds of formulae [Re(4,4’-X2-bpy)(CO)3(PCA)]+ (with X = Me, H, Ph or CO2Me, bpy = 2,2’-bipyridine and PCA = 4-pyridinecarboxaldheyde azine).[2] Changes of photophysical properties in this series have been attributed to an inversion in MO energy levels. As shown in the Figure, we can now support this statement by DFT calculations (with the CPCM solvation model) of the ground states of some of these complexes - including bpz ( = 2,2’-bipyrazine) and 4,4’-CO2H-bpy as auxiliary ligands - dissolved in CH3CN. We have also carried out TDDFT calculations of electronic transitions in the same solvent. The simulated spectra account well for the experimental absorption bands. The results are also consistent with variations of photophysical properties induced by ligand protonations in a related complex in aqueous solutions.[3] References: [1] Vlcek, A. J.; Zalis, S. Coord. Chem. Rev. 2007, 251, 258-287. [2] (a) Cattaneo, M.; Fagalde, F.; Katz, N. E.; Leiva A. M.; Schmehl, R. Inorg. Chem. 2006, 45, 127-136. (b) Cattaneo, M.; Fagalde, F.; Katz, N. E. Inorg. Chem. 2006, 45, 6884-6891. (c) Cattaneo, M.; Fagalde, F.; Katz, N. E.; Borsarelli C. D.; Parella, T. Eur. J. Inorg. Chem. 2007, 34, 5323-5332. Cover Picture p. 5309. [3] Cattaneo, M.; Fagalde, F.; Borsarelli C. D.; Katz, N. E. Inorg. Chem. 2009, 48, 3012-3017.