Details

Autor(en) / Beteiligte

• Mary Sheeba, Mani
• Preethi, Sankaranarayanan
• Nijamudheen, A
• Muthu Tamizh, Manoharan
• Datta, Ayan
• Farrugia, Louis J
• Karvembu, Ramasamy

Titel

Half-sandwich Ru(η6-C6H6) complexes with chiral aroylthioureas for enhanced asymmetric transfer hydrogenation of ketones - experimental and theoretical studiesElectronic supplementary information (ESI) available: A table of the X-ray crystallographic data, atomic coordinates in CIF format, the molecular structures of ligands L2 & L4, 1H NMR and 13C NMR spectra of all the ligands and complexes, and GC and HPLC data are included. Cartesian coordinates, energies, and vibrational frequencies of all

Erscheinungsjahr

2015-09

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• The reactions of [RuCl 2 (η 6 -C 6 H 6 )] 2 with chiral aroylthiourea ligands yielded pseudo-octahedral half-sandwich "piano-stool" complexes. All the Ru( ii ) complexes were characterized by analytical and spectral (UV-visible, FT-IR, 1 H NMR and 13 C NMR) studies. The molecular structures of the ligands (L2 and L4) and the complexes ( 2 , 4 and 5 ) were confirmed by single crystal XRD. All the complexes were successfully screened as catalysts for the asymmetric transfer hydrogenation (ATH) of ketones using 2-propanol as the hydrogen source in the presence of KOH. The ATH reactions proceeded with excellent yields (up to 99%) and very good enantioselectivity (up to 99% ee). The scope of the present catalytic system was extended to substituted aromatic ketones and few hetero-aromatic ketones. Density functional theory (DFT) calculations predicted non-classical, concerted transition states for the ATH reactions. The catalytic activity of Ru-benzene complexes toward asymmetric reduction of ketones was significantly higher compared to that of p -cymene complex analogues. Such enhanced efficiency and product selectivity of Ru-benzene complexes compared to those of Ru- p -cymene complexes were rationalized by the computational study. The efficiency of Ru-benzene complexes towards ATH of ketones was studied.