"Click" tetradentate ligands.

A series of triazole-based N4 tetradentate ligands 1a-d are efficiently synthesized using Cu(I)-catalyzed azide-alkyne "click" strategy and are readily coordinated to many metal ions (e.g. Mn(II), Ni(II), Zn(II) and Fe(II)). The X-ray structures of the resultant metal-complexes (4a-d, 5a, 6a and 7a) reveal an octahedral mononuclear structure with two co-ligands bonded in cis sites and the two triazoles as nitrogen donors to the metal center. The Mn(II)-complexes (4a-d) show efficient catalytic activities in the epoxidation of various aliphatic terminal olefins with peracetic acid, and feature with low catalyst loading, fast conversion and high yields.