Chalcogen (S/Se) Ligated Palladium(II) Complexes of Bulky Ligands: Application in O‐Arylation of Phenol

Abstract

AbstractTwo N‐pyrene based ligands L1 (1‐pyrene‐CH=N(CH2)2‐SPh) and L2 (1‐pyrene‐CH=N(CH2)2‐SePh) with an imine functionality and a chalcogen donor have been synthesized and characterized using 1H as well as 13C NMR spectral techniques. Palladium(II) complexes (1; PdCl2−ĸ2−L1 and 2; PdCl2−ĸ2−L2) of L1 and L2 have been prepared, isolated and characterized using NMR and single crystal X‐ray diffraction studies. The geometry around Pd is nearly square planar in these complexes and ligands are coordinated to the metal centre in a bidentate (S/Se, N) mode. The molecular complexes 1 and 2 have been explored as potential catalysts in O−arylation reaction between substituted aryl halides and phenol. Both the complexes showed excellent efficiency towards this coupling and a TON of 990 (maximum TOF 310) has been achieved using 0.1 mol% of catalyst 2. The effect of the nature of chalcogen donor atom (S/Se) on catalytic efficiency of the complexes has been observed as selenium congener was more efficient than sulphur counterpart.