Design of Air and Moisture Stable Ruthenophane and Ruthenium(II)‐π Complexes and Study of Their Applications in Catalysis

Abstract

AbstractHerein, we report the synthesis and characterization of two ruthenophane (1) and ruthenium(II)‐π (2) complexes, and the results of their catalytic applications under different conditions. These complexes exhibited excellent air and moisture stability due to the existence of effective cation‐π interactions between the metal ion and the aromatic surface of the ligand. These complexes were tested and compared in the transfer hydrogenation of acetophenone in 2‐propanol. The ruthenophane complex 1 exhibited highest efficiency in the catalytic transfer hydrogenation reaction when compared to the complex 2.The better efficiency of the complex 1 can be ascribed to the steric and cation‐π interactions of the cyclophane ligands with the metal centre under reaction conditions. Using catalyst loading of ca. 2 mol%, the transfer hydrogenation of the aromatic ketones having different substituents was achieved. Notably, these complexes exhibited high selectivity for the aromatic ketones having electronegative substituents and showed highest efficiency of ca. 100% under moderate reaction conditions when compared to the literature known ruthenium catalysts.