Synthesis, characterization and a few noticeable properties of Ni(II) complexes embedded with azo (-N=N-) and azomethine (-C=N-) ligands: A brief review

Transition metal complexes incorporating conjugated or non-conjugated azo-azomethine ligands are emergent class compounds in organometallic and catalytic chemistry. Metal complexes with structurally tuneable azo-azomethine ligands have versatile properties and numerous applications in various fields of chemistry. Predominantly, ۳d, ۴d, and a few ۵d transition metal chelates of azo-azomethine ligands with variant features have been reported unequivocally. Geometrical complexity characterizes the rich coordination chemistry of azo-azomethine compounds due to their multiple denticities and the redox non-innocent ligands and metal centres. A detailed literature survey revealed that no brief review has yet been published on azo-imine chemistry with nickel metal. Therefore, the present review article encompasses the research undertaken on the synthetic strategies and coordinating behaviour of various azo-azomethine ligands with nickel metal centres and a few significant properties of metal complexes.