Preparation of trinuclear ruthenium clusters based on piconol ligands and their application in Oppenauer-type oxidation of secondary alcohols

Treatment of Ru-3(CO)(12) with one equivalent of 2-indolyl-6-pyridinyl-alcohol ligands 2-(C8H6N)-6-((CRROH)-R-1-O-2)C5H3N (R-1 = R-2 = Me (L1H); R-1 = R-2 = C2H5 (L2H); R-1, R-2 = -(CH2)(4)- (L3H);& R-1, R-2 = -(CH2)(5)- (L4H)) in refluxing THF afforded the corresponding trinuclear ruthenium clusters L(mu(2)-H)Ru-3(CO)(9) (1a-1d), respectively. All the novel Ru complexes were well characterized by NMR, elemental analyses and IR spectra. Structures of complexes 1a, 1c, and 1d were further determined by X-ray crystallographic studies. Complexes 1a-1d were applied to catalytic Oppenauer-type oxidation of secondary alcohols with acetone as oxidant, and complex 1a was found to be the most efficient catalyst.

Automated summary

New trinuclear ruthenium clusters were synthesized with different ligands, characterized by NMR, elemental analyses, and IR spectra, with the structures of 1a, 1c, and 1d further confirmed by X-ray crystallography. These complexes were utilized in the Oppenauer-type oxidation of secondary alcohols with acetone as the oxidant, of which complex 1a exhibited the highest catalytic efficiency.