Electrochemical Reductive Deprotonation of an Imidazole Ligand in a Bipyridine Tricarbonyl Rhenium(I) Complex

Abstract

AbstractThe reduction pathway of fac‐[ReI(imH)(CO)3(bpy)]+ was studied in situ by UV/Vis/NIR–IR spectroelectrochemistry with an OTTLE cell. The complex underwent 1e– reduction of the 2,2′‐bipyridine (bpy) ligand and intramolecular electron transfer, which resulted in the conversion of the axial imidazole (imH) ligand to 3‐imidazolate (3‐im–). This step was followed by two bpy‐based 1e– reductions to ultimately produce five‐coordinate [Re(CO)3(bpy)]– and free 3‐im–. The identity of the reduction product fac‐[Re(3‐im–)(CO)3(bpy)] has been proven by partial chemical deprotonation of the parent complex followed by IR spectroelectrochemistry. This is the first time that the reductive electrochemical conversion of metal‐coordinated imidazole to terminal 3‐imidazolate has been observed.