Synthesis, characterization, and catalytic activity of half‐sandwich ruthenium complexes with pyridine/phenylene bridged NHC = E (NHC = N‐heterocyclic carbene, E = S, Se) ligands

Abstract

Three half‐sandwichruthenium(II) complexes with pyridine/phenylene bridged NHC = E (NHC = N‐heterocyclic carbene, E = S, Se) ligands [Ru(p‐cymene)L](PF6)1–2 (1a–1c, L = ligand) were synthesized and characterized. All ruthenium complexes were fully characterized by 1H and 13C NMR spectra, mass spectrometry, and single‐crystalX‐ray diffraction methods. Moreover, the half‐sandwich ruthenium complexes with NHC = E ligands showed highly catalytic activities towards to the tandem dehydrogenation of ammonia borane (AB) and hydrogenation of R–NO2 to R–NH2 at 353 K in water.

Ru(II) and Ru(III) complexes containing N‐acylthiourea ligands: Supramolecular structures and synthons, reduction, and reaction pathway of aromatic nitro compounds

“…The reduction of aromatic nitro compounds to aromatic amino compounds is one of the most important reactions in the chemical industry 19,20 because amino compounds are important intermediates in the preparation of agrochemicals, dyes, pigments, and pharmaceuticals 21–23 . Direct hydrogenation of nitro compounds to related amines is an efficient and fundamental strategy 24 . Hydrogen gas is used efficiently in the reduction of nitro compounds 25 but generally requires a high reaction temperature and a high H 2 pressure 24 .…”

“…Ruthenium complexes are widely used as homogeneous catalysts in the reduction reactions of nitro compounds due to their high catalytic activity 24,26–28 . However, to the best of our knowledge, the use of Ru complexes containing RuCl 2 (PPh 3 ) 3 and RuHCl(CO)(PPh 3 ) 3 salts with N ‐acyl thiourea ligands as homogeneous catalysts for the hydrogenation of nitroarenes has not yet been reported.…”

“…[21][22][23] Direct hydrogenation of nitro compounds to related amines is an efficient and fundamental strategy. 24 Hydrogen gas is used efficiently in the reduction of nitro compounds 25 but generally requires a high reaction temperature and a high H 2 pressure. 24 Transfer hydrogenation offers an attractive alternative to avoid the use of combustible hydrogen gas, creating more environmentally benign conditions.…”

“…24 Hydrogen gas is used efficiently in the reduction of nitro compounds 25 but generally requires a high reaction temperature and a high H 2 pressure. 24 Transfer hydrogenation offers an attractive alternative to avoid the use of combustible hydrogen gas, creating more environmentally benign conditions. In the literature, there are many reports of transfer hydrogenation agents used in nitro reduction such as sodium tetrahydroborate, ammonia borane (NH 3 ÁBH 3 ), alcohol, and hydrazine under mild reaction conditions.…”

“…26 Ruthenium complexes are widely used as homogeneous catalysts in the reduction reactions of nitro compounds due to their high catalytic activity. 24,[26][27][28] However, to the best of our knowledge, the use of Ru complexes containing RuCl 2 (PPh 3 ) 3 and RuHCl(CO) (PPh 3 ) 3 salts with N-acyl thiourea ligands as homogeneous catalysts for the hydrogenation of nitroarenes has not yet been reported. Therefore, in this study, we performed the synthesis and characterization of paramagnetic Ru(II) and diamagnetic Ru(III) complexes with two benzoylthiourea derivative ligands.…”