Half-Sandwich Ruthenium Complexes with Schiff-Base Ligands: Syntheses, Characterization, and Catalytic Activities for the Reduction of Nitroarenes

A series
of ruthenium­(II) p-cymene complexes containing
Schiff-base ligands [Ru­(p-cymene)­LCl] [HL = pyridyl-salicylimine
(2a–2d); HL = thiazol-salicylimine
(2e–2h); HL = benzothiazol-salicylimine
(2i–2l)] have been synthesized and
characterized. All Schiff-base ligands and half-sandwich ruthenium
complexes were fully characterized by 1H and 13C NMR spectra, mass spectrometry, and infrared spectrometry. The
molecular structures of ruthenium complexes 2b and 2k were further confirmed by single-crystal X-ray diffraction
methods. Furthermore, these half-sandwich ruthenium complexes are
active catalysts for the mild hydrogenation of nitroarenes to aromatic anilines in
the presence of sodium tetrahydroborate reducing agent in water. The
most efficient catalyst, 2b, was found be compatible
with nitroarenes of various functional groups.