Synthesis, structure and catalytic activity of manganese(ii) complexes derived from bis(imidazole)methane-based ligands

Abstract

New mononuclear manganese(II) complexes [Mn(κ²-L1)(OAc)₂] ([Mn]-1), [Mn(κ²-L2)(OAc)₂] ([Mn]-2) and [Mn(κ²-L3)(OAc)₂] ([Mn]-3) with imidazole based ligands {4,4′-(phenylmethylene)bis(2-ethyl-5-methyl-1H-imidazole)} (L1), {(4,4′-((2-methoxy phenyl)methylene)bis(2-ethyl-5-methyl-1H-imidazole)} (L2) and {4,4′-((2-chlorophenyl) methylene)bis(2-ethyl-5-methyl-1H-imidazole)} (L3) are synthesized and fully characterized by a variety of techniques. Furthermore, the molecular structures of complexes [Mn]-1 and [Mn]-2 are established by single crystal X-ray structure analysis. The synthesized manganese(II) complexes exhibited efficient catalytic oxidative coupling of primary amines in air under solvent-free conditions to the corresponding imines in moderate to good yields.