A series of acac-ruthenium complexes with chiral Schiff base ligands: Synthesis, characterization and catalytic property

Abstract

Four acac ruthenium precursors Ru(acac)2(n-PrCN)2 (acac = acetylacetonate) (1), Ru(acac)2(PhCN)2 (2), [Ru(hfac)(CH3CN)4](CF3SO3) (hfac = 1,1,1,5,5,5-hexafluoroacetylacetonate, 3), and Ru(acac)(dmso)3Cl (dmso = dimethyl sulfoxide) (4) were synthesized. Reactions of ruthenium precursor Ru(acac)2(n-PrCN)2 and chiral Schiff bases HLn afforded a series of Ru(acac)2Ln adducts (n = 1‒9) and a trinuclear ruthenium Schiff base complex (S)-(HNEt3)[(η3-O,N,O-L3)2Ru{μ-(η1-O-L3)4RuCl}Ru(η3-O,N,O-L3)2] (5). All complexes were characterized by NMR, FT-IR, HR-MS, and UV–vis spectroscopies along with electrochemistry properties. The structures of chiral Schiff base ligands (R)-HL8 and (S)-HL9, and ruthenium complexes 1–5 were unambiguously established by single-crystal X-ray diffraction. The good catalytic property of nine Ru(acac)2Ln complexes and the trinuclear ruthenium complex 5 with chiral Schiff base ligands for cyclopropanation of styrene was also presented.