Synthesis of six 8-quinolinate-based ruthenium complexes with high catalytic activity for nitroarene reduction

Abstract

Six ruthenium complexes were synthesized by treating different 2-substituted 8-hydroxyquinolinate ligands with [Ru(p-cymene)(μ-Cl)Cl]2. Their structures were fully characterized by a variety of techniques, including 1H and 13C NMR spectra, elemental analyses and infrared spectrometry. Additionally, single-crystal X-ray diffraction reveals that these ruthenium complexes possess similar half-sandwich structures. The mononuclear ruthenium building units are further linked into 1D or 2D supramolecular structures through non-covalent interactions, such as π⋯π stacking, hydrogen-bonding and CH⋯ halogen interactions. The catalytic activities of the six half-sandwich ruthenium complexes towards the hydrogenation of nitroarenes were explored under mild conditions. The ruthenium complexes displayed high catalytic activities in the synthesis of aromatic anilines from nitroarenes in the presence of NaBH4.