Activation of ortho C–H bond by nickel(II) acetate or sodium tetrachloropalladate(II) in naphthyl imino derivatives of azobenzene

The reactions of 1-{[2-(arylazo)phenyl]iminomethyl}-2-naphthol, H2Lnap [where H represents the dissociable proton upon complexation and aryl groups of H2Lnap are phenyl for H2L1nap; p-methyl phenyl for H2L2nap and p-chloro phenyl for H2L3nap] with nickel acetate tetra hydrate or disodium tetrachloropalladate in methanol afforded M–C(aryl) bonded species of composition [M(Lnap)] (M = Ni(II) and Pd (II)). The dinegative (Lnap)2− ligands bind the Ni(II) or Pd(II) in tetradentate (C, N, N, O) fashion in distorted square planar geometry. Ligands and complexes were characterized by spectroscopic methods. The X-ray structures of H2L1nap, [Ni(L1nap)] and [Pd(L1nap)] were determined to authenticate the characterization. Reactions with metachloroperbenzoic acid (mCPBA), TBHP and hydrogen peroxide leading to oxygen insertion into the M-C bond have been examined. Luminescent properties of ligands and complexes have been reported.

Graphical abstractOrthometallated Ni(II) and Pd (II) complexes incorporating azosalen ligands have been synthesized and characterized. The dinegative ligands bind the metal ions in tetradentate (C, N, N, O) fashion. Structures were confirmed by X-ray study. Oxygen insertion into the M–C bond using mCPBA or hydrogen peroxide has been examined. Luminescence properties of ligands and complexes have been studied and compared.Figure optionsDownload full-size imageDownload as PowerPoint slide