Syntheses, characterization, and electrochemical behavior of alkylated 2-(2′-quinolylbenzimidazole) complexes of rhenium (I)

Abstract

A series of ClRe(CO) 3 -containing complexes with 1-methyl-1H-benzo[d]imidazol-2-yl)quinoline (Me-QuBIm), 1-benzyl-1H-benzo[d]imidazol-2-yl)quinoline (Bn-QuBIm), and 2-(1-(4-methoxybenzyl)-1H-benzo[d]imidazol-2-yl)quinoline (OMeBn-QuBIm) ligands were prepared and characterized. Each complex was characterized using 1 H and 13 C NMR, infrared, UV–vis, and fluorescence spectroscopies, and cyclic voltammetry. The physical properties of each complex are similar to the parent ClRe(CO) 3 (2-(1H-benzo[d]imidazol-2-yl)quinoline) complex. However, the electrochemical behavior is distinct from the parent, showing reversible voltammograms and poor CO 2 reduction activity. Addition of K + or Mg 2+ as Lewis acids modestly increases catalytic currents, but at large overpotentials. The work presented here is consistent with a mechanism that involves rhenium reduction and deprotonation of imidazole and benzimidazole prior to CO 2 reduction electrocatalysis.