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

Abstract

Treatment of Ru3(CO)12 with one equivalent of 2‐indolyl‐6‐pyridinyl‐alcohol ligands 2‐(C8H6N)‐6‐(CR1R2OH)C5H3N (R1 = R2 = Me (L1H); R1 = R2 = C2H5 (L2H); R1, R2 = −(CH2)4‐ (L3H);& R1, R2 = −(CH2)5‐ (L4H)) in refluxing THF afforded the corresponding trinuclear ruthenium clusters L(μ2‐H)Ru3(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.

Selective oxidation of C (sp3)—H bonds enabled by ruthenium clusters containing pyridine‐alkoxide ligands

“…The hydrido resonances are at δ À10.41 (1), À10.55 (2), À11.02 (3), and À10.59 (4), respectively. [33] The 13 C NMR spectra of the clusters have several peaks around 183.4-205.9 ppm assigned to the terminal carbonyls.…”