Azide‐Alkyne Cycloaddition Reaction Catalyzed by Cu(II) Complexes: Studies on the effect of Different Ligand Systems

Abstract

AbstractA series of bidentate ligands L1–L6 (where L1=2‐(2‐(diphenylmethylene)‐1‐phenylhydrazinyl)pyridine, L2=(E)‐2‐(2‐benzylidene‐1‐phenylhydrazinyl)pyridine, L3=(E)‐2‐(2‐(4‐methoxybenzylidene)‐1‐phenylhydrazinyl)pyridine, L4=(E)‐2‐(2‐(4‐chlorobenzylidene)‐1‐phenylhydrazinyl)pyridine, L5=(E)‐2‐(2‐(4‐nitrobenzylidene)‐1‐phenylhydrazinyl)pyridine, L6=(E)‐N,N‐dimethyl‐4‐((2‐phenyl‐2‐(pyridin‐2‐yl)hydrazono)methyl)aniline) were synthesized and characterized using reported literature.[1–4] Ligands were reacted with Cu(NO3)2 metal salt to synthesize metal complexes [Cu(L1‐6)(ONO2)(H2O)]NO3 i. e., (C1–C6). Metal complexes were characterized by IR, UV‐Visible, TGA and ESI‐MS spectral methods. The molecular structure of complex C2 was analyzed by single crystal X‐ray technique. Complexes were employed as catalysts to perform click reaction. The catalytic reaction was also observed in situ by reacting ligands with Cu(NO3)2 metal salt in presence of sodium ascorbate. The role of substituents present in the ligand frame of metal complexes were studied, and a probable mechanism was proposed.