Half-Sandwich Ruthenium Complexes with Hydrazone Ligands: Preparation, Structure, and Catalytic Activity in Cyanosilylether Synthesis under an Air Atmosphere

Abstract

A new class of N,O-coordinate half-sandwich ruthenium complexes supported by hydrazone ligands with a general formula of [Ru(η 6p-cymene)Cl(L)] have been obtained in moderate to excellent yields conveniently. These air-and moisture-stable ruthenium complexes exhibited excellent catalytic activity in cyanosilylether synthesis under mild reaction conditions. Under the catalysis of ruthenium, various cyanosilylethers with different substituents were obtained through a one-pot reaction of trimethylsilyl cyanide with carbonyl substrates, with good to excellent yields. Excellent catalytic efficiency, a wide substrate range, and mild reaction conditions made this type of ruthenium catalyst have potential for industrial application. All of the half-sandwich ruthenium complexes have been well described by infrared, nuclear magnetic resonance, and EA analysis. Molecular structures of ruthenium complexes 1 and 4 were confirmed by single-crystal X-ray analysis.

Half-sandwich iridium complexes with hydrazone ligands: preparation, structure, and catalytic synthesis of cyanosilylethers under air

“…The stretch bands at approximately 1349–1360 cm −1 suggested the coordination of the C–O bond to the iridium center through the enolization configuration. 21 In the 1 H NMR spectra of the prepared iridium complexes 1–4 , the disappeared peaks of –OH protons of the free ligand in the range of δ 9.0 ppm indicated that the hydrazone ligands underwent deprotonation during the reaction with the iridium precursor. Multiple groups of signals were observed in the range of δ 7.00–8.50 ppm due to the aromatic protons of the hydrazone ligands of the iridium complexes.…”

“…9–20 Although various types of catalytic systems have been developed, drawbacks such as the instability of the catalyst, harsh conditions, and narrow substrate scope have limited their applications. Recently, our group reported the ruthenium-catalyzed cyanosilylation reaction; 21 however, there are relatively few reports of hydrazone-based N , O -chelate half-sandwich iridium complexes as catalysts to catalyze the cyanosilylation reaction. This motivated us to explore a new type of catalyst for stable, simple synthesis, and efficient catalysis of the iridium complex.…”

Half-sandwich ruthenium complexes with acylhydrazone ligands: synthesis and catalytic activity in the N-alkylation of hydrazides

“…The Ru–N (2.10 Å) and Ru–O (2.06 Å) bond lengths were located in the regular range compared with the reported analogous complexes. 24…”