Tricarbonyl triazolato Re(i) compounds of pyridylbenzimidazole ligands: spectroscopic and antimicrobial activity evaluation.

Catalyst-free [3+2] cycloaddition coupling between [Re n (N 3 ) n (CO) 3 n L] ( n = 1, L = 1-ethyl-2-(pyridin-2-yl)benzimidazole (L 1 ) and n = 2, L = 1,1'-(hexane-1,6-diyl)bis[2-(pyridin-2-yl)-1 H -benzimidazole] (L 2 )) and dimethyl acetylene dicarboxylate (DMAD) afforded mono- and binuclear triazolate complexes. Spectroscopic data presented unambiguous evidence for isomerization of the kinetically formed N(1) bound triazolate isomer into the N(2) analogue. The solvatochromism properties were assessed by UV/Vis spectroscopy with the aid of time dependent density functional theory calculations. The free ligands and their tricarbonyl triazolato Re(i) complexes were screened for their potential antimicrobial activity against different bacterial and fungal pathogens.