Ruthenium -p- cymene complexes with acylthiourea, and its heterogenized form on graphene oxide act as catalysts for the synthesis of quinoxaline derivatives

Synthesis of a series of half-sandwich Ru(II) complexes ( 1 -5 ) containing acylthiourea ligand is reported herein. All the Ru(II) complexes were well characterized by analytical and spectroscopic (UV-Vis, FT-IR, NMR and mass spectrometry) methods. Molecular structures of two ( 2 and 3 ) of the complexes were confirmed by single crystal X-ray diffraction, and the complexes adopted pseudo-octahedral geometry around Ru. Catalytic ability of the Ru complexes was evaluated in the synthesis of quinoxaline com-pounds from various 2-nitroaniline and hydroxy ketone derivatives via transfer hydrogenation approach. Active homogeneous catalyst was heterogenized by supporting it on graphene oxide, and the heteroge-neous equivalent was characterized by Raman, XPS, TEM, SEM and ICP-OES techniques. Activity of the heterogeneous catalyst was tested, and it can be reused up to five cycles without any loss in activity. (c) 2021 Elsevier B.V. All rights reserved.

Automated summary

A series of half-sandwich Ru(II) complexes containing acylthiourea ligand were reported with well-characterized analytical and spectroscopic methods. The catalytic ability of Ru complexes in the synthesis of quinoxaline compounds via transfer hydrogenation approach was evaluated, and an active homogeneous catalyst was heterogenized by supporting it on graphene oxide. The heterogeneous catalyst showed good reusability up to five cycles without any loss in activity.