[Fe(bpy)Cl 3 X][bpy H] complexes: synthesis, characterization and theoretical studies towards visible-light photocatalytic hydroxyethylation of quinoline

A series of [Fe(bpy)Cl3X][bpy·H] (X = Cl, Br, I) complexes were prepared from direct treatment of FeCl3·6H2O with 2,2′-bipyridine in the presence of an HX solution. The complexes were characterized by IR, UV–Vis, XRDP, and cyclic voltammetry techniques. Electrochemical studies revealed a possible reduction to form the corresponding Fe0 complexes. A single crystal of [Fe(bpy)Cl4][bpy·H] displayed important H–Cl/Cl–H, H–H, H–C/C–H, and H–N/N–H interactions which were corroborated by a Hirshfeld surface analysis as well as MEP, QTAIM, and NCI studies, and complemented by HOMO/LUMO calculations at the B3LYP/cc-pVDZ + LANL2DZ level. In addition, the complexes displayed catalytic activity for the visible-light-driven the formation of 1-quinolin-4-yl-ethanol from quinoline under acidic conditions.