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

A series of hydrazone-based N,O-chelate half-sandwich iridium complexes were synthesized through a facile route with good yields. These air- and moisture-stable iridium complexes exhibited excellent catalytic activity in the cyanosilylether synthesis under mild reaction conditions. Under the catalysis of iridium, various cyanosilylethers with different substituents were obtained through a one-pot reaction of trimethylsilyl cyanide (TMSCN) with carbonyl substrates, with good to excellent yields. The excellent catalytic efficiency, wide substrate range, and mild reaction conditions made this type of iridium catalyst have the potential for industrial applications. All the half-sandwich iridium complexes were well characterized by IR, NMR, and EA analyses. The molecular structure of iridium complex 1 was confirmed by single-crystal X-ray analysis.