Highly efficient phosphine-free half-sandwich Ruthenium(II) catalysts for hydrogenation of nitroarenes

We present herein the synthesis and characterization of two ruthenium(II) half-sandwich complexes (1 & BULL;PF6 and 2 & BULL;PF6) featuring phosphine-free ligands N-(pyridin-2-yl)quinolin-2-amine (L-1) and N-(4-methylpyridin-2-yl) quinolin-2-amine (L-1). The molecular structures of both complexes were determined by single-crystal X-ray diffraction. These complexes functioned as excellent phosphine-free catalytic systems for the synthesis of aryl amines from corresponding nitroarenes by employing sodium borohydride under mild conditions in ethanol. Intermediacy of [Ru-H] has been established by spectroscopic studies. The reduction showed good chemo selectivity in presence of-COOH and -NHCOMe functionality.

Automated summary

This study presents the synthesis and characterization of two ruthenium(II) half-sandwich complexes (1 & BULL;PF6 and 2 & BULL;PF6) with phosphine-free ligands N-(pyridin-2-yl)quinolin-2-amine (L-1) and N-(4-methylpyridin-2-yl) quinolin-2-amine (L-1). The molecular structures of both complexes were determined using single-crystal X-ray diffraction. These complexes acted as excellent phosphine-free catalytic systems for the mild synthesis of aryl amines from nitroarenes using sodium borohydride in ethanol. Spectroscopic studies confirmed the intermediacy of [Ru-H], and the reduction showed good chemo selectivity in the presence of -COOH and -NHCOMe functionalities.