Synthesis, structure, characterization and one pot catalytic activity of half-sandwich iridium(III) complexes

Abstract

A series of stable mononuclear half-sandwich iridium(III) complexes of the general formula [(η⁵-C₅Me₅)Ir(L)Cl](BPh₄) has been synthesized in dry methanol using different imino pyridine ligands (L₁–L₆) and [(η⁵-C₅Me₅)₂Ir₂(µ-Cl)₂Cl₂] in a 2:1 molar ratio. All complexes were fully characterized by melting point, CHN analysis, FT-IR, UV–visible, ¹H NMR, ¹³C NMR spectroscopy and mass spectrometry. The structure of complex 3 [(η⁵-C₅Me₅)Ir(L₃)Cl](BPh₄) was determined by single crystal X-ray structure analysis, showing a chelating coordination mode of the imino pyridine L₃. One pot organic transformations of aldehyde to amide were carried out by complexes 1–6 in toluene at 110 °C in the presence of hydroxyl amine hydrochloride and sodium bicarbonate. The catalytic activity of complex 3 was found to be excellent, showing high conversion with catalytic turnover frequency up to 500.