Syntheses, Structures, and Reactions of Cyclometalated Rhodium, Iridium, and Ruthenium Complexes of N-Methoxy-4-nitrobenzamide

Abstract

The cyclometalated rhodium, iridium, and ruthenium complexes of N-methoxy-4-nitrobenzamide were synthesized by treatment of N-methoxy-4-nitrobenzamide with [Cp*MCl2]2] (M = Rh and Ir) or [(p-cymene)RuCl2]2 via C–H bond activation. The molecular structures of all these complexes were determined by single-crystal X-ray diffraction analysis. When the cyclometalated rhodium and ruthenium complexes were used as catalysts in the C–H bond functionalization reactions reported before, the desired products were obtained in high yields, proving that these cyclometalated complexes were probably the key catalytic intermediates of the C–H bond functionalization reactions of N-methoxybenzamide derivatives. The stoichiometric reactions of the cyclometalated rhodium, iridium, and ruthenium complexes with diphenylacetylene afforded the corresponding seven-membered metallacycles with insertion of two molecules of diphenylacetylene in 24, 6, and 20% yields, respectively, through the tandem reaction. However, the cyclometalat...