Syntheses and Applications of Symmetrical Dinuclear Half-Sandwich Ruthenium(II)–Dipicolinamide Complexes as Catalysts in the Transfer Hydrogenation of Ketones

The treatment of [Ru(η6-p-cymene)Cl2]2 with N,N’-(1,2-phenylene)dipicolinamide (H2L1) afforded the double salt complex [{Ru(η6-p-cymene)2-µ-Cl}L1][Ru(η6-p-cymene)Cl3], (Ru1) in moderate yields. Separately, reactions ligands (H2L1), N,N’-(4,5 dimethyl-1,2-phenylene)dipicolinamide (H2L2), and N,N’-(4-methoxy-1,2-phenylene)dipicolinamide (H2L3) presence KPF6 respective dinuclear half-sandwich Ru(II) complexes [{(Ru(η6-p-cymene)2--µ-Cl}L1][PF6] (Ru2), [{(Ru(η6-p-cymene)2-µ-Cl}L2][PF6] (Ru3), [{(Ru(η6-p-cymene)2-µ-Cl}L3][PF6] (Ru4). NMR FT-IR spectroscopies, ESI-MS spectrometry, elemental analyses were used to establish molecular structures new ruthenium(II) complexes. Single crystal X-ray crystallography was confirm piano-stool geometry Ru1 Ru4, as containing N^N chelated ligand bridging chlorido each atom. (Ru1-Ru4) showed good catalytic activities at low catalyst concentrations 0.005 mol% transfer hydrogenation a wide range ketone substrates.