N-Substituted Iminopyridine Arene–Ruthenium Complexes for the Regioselective Catalytic Hydration of Terminal Alkynes

Abstract

A series of N-substituted iminopyridine ligand-based arene–RuII complexes with general formula [(η6-arene)Ru(C5H4N-2-CH=NR)Cl]+ was synthesized and characterized by NMR spectroscopy, mass spectrometry, and single-crystal X-ray diffraction studies. The synthesized arene–RuII complexes showed high activity in the regioselective Markovnikov hydration of a range of aromatic and aliphatic terminal alkynes and produced moderate to good yields of the corresponding methyl ketones. Moreover, the RuII catalysts studied showed good recyclability. The mechanism of the RuII-catalyzed hydration reaction was investigated in detail by performing mass experiments and control experiments, followed by the identification of crucial RuII–alkyne and RuII–vinyl organometallic species.