Mechanochemical synthesis of half‐sandwich iridium/rhodium complexes with 8‐hydroxyquinoline derivatives ligands

Abstract

Mechanochemistry provides a rapid, efficient route to half‐sandwich iridium and rhodium complexes from [MCp*(μ‐Cl)Cl]2 (M = Ir, Rh) and 8‐hydroxyquinoline‐2‐carbaldehyde without the need for Schlenk manipulation, inert gas protection, or dry solvents. Furthermore, post‐synthetic modification of the half‐sandwich metal complexes has been carried out via a mechanochemical Wittig reaction between half‐sandwich metal complex and phosphorus ylide. All complexes were fully characterized by 1H and 13C NMR spectra, infrared spectroscopy, mass spectrometry, and single‐crystal X‐ray diffraction method. The half‐sandwich rhodium complexes exhibited high catalytic activity towards the amide synthesis between aldehyde and hydroxylamine hydrochloride (NH2OH·HCl) with a broad functional group tolerance.

Kinetic Analysis of Consecutive/Parallel Transformation of Furfural to Biomass-Based Primary Amide by Using a “Concentration–Time” Integral

“…The developed catalysts should be able to consecutively catalyze the tandem procedure of 2 dehydration and nitrile ( 3 ) rehydration (Scheme a), thus being a big challenge for organic transformation. Compared with the rearrangement of aldoxime to primary amide, a direct amidation of aldehyde ( 1 ) with hydroxylamine (H 2 NOH) offers a more efficient and practical approach to primary amide (Scheme b), in which both aldoxime and nitrile were generally observed as in-situ-formed intermediates. , However, the reported catalytic systems were generally limited to transition-metal-based homogeneous catalysts such as Sc, Fe, , Cu, ,− Ru, ,− Rh, Pd, and Ir , (see Table S1 in the Supporting Information). Therefore, development of an efficient, robust, recyclable, and eco-friendly heterogeneous nanocatalysts plays a critical role in the green transformation of aldehyde to primary amide.…”