Pd(II)‐NNN Pincer Complexes for Catalyzing Transfer Hydrogenation of Ketones

Abstract

AbstractChiral and achiral Pd(II)‐NNN pincer complexes (1–3) containing acetonitrile as an ancillary ligand were synthesized and characterized by spectroscopic (UV‐visible, FT‐IR, NMR and mass) techniques. Polarimetric experiments were employed to measure the specific rotation values of the chiral complexes {[α]D27= +135° (2) and −136° (3)}. The structures resolved through single crystal X‐ray diffraction technique disclosed the distorted square planar geometry of the complexes. Transfer hydrogenation (TH) reactions of ketones were carried out in order to appraise the catalytic efficiency of the complexes. Remarkably, the TH results were promising for all the complexes, however, the chiral complexes (2 and 3) failed to induce chirality. Further probe led us to believe that the pincer complexes turned into Pd particles in situ and the later acted as an active catalyst. The scope of TH was extended to various substituted aromatic and heterocyclic ketones (Conversions=75–99%).