[NN]-Chelate nickel complexes with Schiff base ligands: Synthesis, structure and catalytic activity in green amidation reaction

A series of N,N-coordinate nickel (II) complexes with Schiff base ligands have been synthesized. All N,N-coordinate nickel (II) complexes 1-4 were well characterized by IR and elemental analysis. Molecular structure of complex 1 was further characterized by single crystal X-ray diffraction analysis. All air and moisture stable nickel complexes showed efficient catalytic activity for the amidation reaction of a widely range of amides and primary alcohols. N-alkylated amides were given in good to excellent yields with liberating water as the sole byproduct. A variety types of functional groups tolerated well in such reaction condition. In addition, control experiments were carried out to understand this Ni-catalysis protocol.

Automated summary

A series of N,N-coordinate nickel (II) complexes with Schiff base ligands have been synthesized and characterized. The nickel complexes showed efficient catalytic activity in the amidation reaction, yielding high product yields with water as the sole byproduct. The results also demonstrated that the catalytic system exhibited good stability and catalytic performance under different functional group conditions.