Synthesis and catalytic activity of half-sandwich iridium complexes with acylhydrazone ligands for N-alkylation of hydrazides under mild conditions

A new [Cp*IrClL] half-sandwich iridium complex was successfully synthesized by coordinating an acylhydrazone ligand with [Cp*IrCl2]2, followed by comprehensive characterization using various spectroscopic and analytical techniques. Complex 3 was subjected to crystal structure analysis, revealing that the acylhydrazone ligand coordinates with the iridium through bidentate coordination involving the imidolate oxygen and imine nitrogen atoms. This interaction resulted in the formation of a pseudo-octahedral geometry with the iridium center. The iridium complexes 1-4, which are stable in the presence of air and moisture, exhibit significant catalyst performance in the N-alkylation reactions of hydrazides under gentle reaction conditions. This iridium complex catalyzes various types of alcohols to undergo N-alkylation reactions with acyl hydrazides via a one-pot method, yielding diverse N-alkylated hydrazide derivatives. The catalyst displayed exceptional catalytic efficiency, a broad variety of substrates, and gentle reaction conditions, indicating its significant potential for industrial applications. Half-sandwich iridium complexes based on pyrrole hydrazide ligands were synthesized which exhibit excellent catalytic efficiency in the N-alkylation of acyl hydrazides using alcohols as coupling partners. This catalytic system demonstrates broad substrate scope, catalyst stability, mild reaction conditions, and high product yields, making it attractive for industrial production. image