Ruthenium(II) carbonyl complexes containing pyridine carboxamide ligands and PPh3/AsPh3/Py coligands: Synthesis, spectral characterization, catalytic and antioxidant studies

New ruthenium(II) carbonyl complexes bearing pyridine carboxamide and triphenylphosphine/triphenylarsine/pyridine have been prepared by direct reaction of ruthenium(II) precursors with some pyridine carboxamide ligands, N,N-bis(2-pyridinecarboxamide)-1,2-ethane (H2L1), N,N-bis(2-pyridinecarboxamide)-1,2-benzene (H2L2) and N,N-bis(2-pyridinecarboxamide)-trans-1,2-cyclohexane (H2L3). The organic ligands offering two Namide and two Npyridine donor sites to the metal centre. They have been characterized by elemental analyses, FT-IR, UV–Visible, NMR (1H, 13C and 31P) and ESI-MS techniques. Based on the above data, an octahedral structure has been assigned for all the complexes. The catalytic efficiency of the complexes in transfer hydrogenation of ketones in the presence of iPrOH/KOH and N-alkylation of amine in the presence of tBuOK was examined. Furthermore, the antioxidant activity of the ligands and its ruthenium(II) complexes were determined by DPPH radical, nitric oxide radical, hydroxyl radical and hydrogen peroxide scavenging methods, which indicates that the ruthenium(II) complexes exhibit more effective antioxidant activity than the ligands alone.

Graphical abstractRuthenium(II) pyridine carboxamide complexes were synthesized and characterized. They have been assigned an octahedral structure. The new complexes were found to be efficient catalyst for transfer hydrogenation of ketones and N-alkylation of amine. The complexes also exhibited excellent antioxidant (DPPH radical, NO radical OH radical and H2O2 scavengers) activities.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Ruthenium(II) pyridine carboxamide complexes were synthesized and characterized. ► They have proved to be an efficient catalyst for the transfer hydrogenation of ketones. ► The catalytic efficiency of the complexes in N-alkylation of amine was examined. ► Ruthenium(II) complexes also exhibit good antioxidant activity.