Norharmane and Pterin rhenium(I) polypyridyl complexes: synthesis, structural and spectroscopic Characterization

EZEQUIEL WOLCAN; IVÁN MAISULS; FABRICIO RAGONE; OSCAR E. PIRO; GUSTAVO A. ECHEVERRÍA; GABRIELA PETROSELLI; ROSA ERRA-BALLSELS; FRANCO M, CABRERIZO; GUSTAVO T. RUIZ

Iguazú

Congreso; 6 th Latin American Symposium on Coordination and Organometallic Chemistry/6to Simposio Latinoamericano de Química de Coordinación, and Humboldt Kolleg: German-Latin American Symposium on Organometallic and Coordination Chemistry.; 2017

SILQCOM

Two novel Re(I) complexes with the general formula fac-[Re(CO)3(L)(nHo)]CF3SO3, where L = 2,2´-bipyridine (bpy) or 1,10phenanthroline (phen) and nHo (9H-pyrido[3,4-b]indole; norharmane) havebeen synthesized. The Re(I)-nHo complexes were characterized bystructural X-ray diffraction, 1H and 13C NMR, UV-vis absorption and FT-IRspectroscopy, and by a combination of two mass spectrometry techniques,namely ESI-MS and UV-MALDI-MS. All characterizations showed that nHo iscoordinated to the metal atom by the pyridine nitrogen of the molecule. X-raystructural analysis revealed that the crystal lattices for both complexes arefurther stabilized by a strong >N-H...O bond between the pyrrole NH group ofthe pyridoindole ligand and one oxygen atom of thetrifluoromethanesulfonate counter-ion. Ground state geometry optimizationby DFT calculations showed that in fluid solution the nHo ligand may rotatefreely. The nature of the electronic transitions of Re(CO)3(bpy)(nHo)+ wereestablished by TD-DFT calculations. The set of the most important electronictransitions present in this complex are comprised of pi-pi* electronictransitions centered on bpy and nHo moieties, LLCT(nHo->COs),MLLCT(Re(CO)3->bpy) and LLCT(nHo->bpy) transitions. Additionally, TDDFTcalculations predict the existence of another two intenseMLLCT(Re(CO)3->nHo) electronic transitions. Calculated UV-vis absorptionspectra are in good agreement with the corresponding experimental data forthe bpy-containing complex.