**Abstract**

Primary amines are combined with an aldehyde group to generate Schiff base compounds, which are called condensation imine products. This class of compounds has a general structure, R-C=NR', where R and R' represent alkyl/aryl/cyclohexyl/ heterocyclic group. These compounds contain an azomethine group that is basic in nature due to, (i) the presence of lone pair of electrons on the nitrogen and (ii) electron-donating nature of the double bond. Hence, these compounds, as ligands, participate in the formation of metal complexes. The presence of lone pair of electrons on the nitrogen atom and the hybridization involved explains the physical, chemical, and spectral properties of nitrogen-containing moieties. In the case of (sp<sup>2</sup> ) hybridization (trigonal structure), the lone pair of electrons occupies either a symmetrical unhybridized 2p orbital that is perpendicular to the plane of trigonal hybrids or a symmetrical hybrid orbital, whose axis is in the plane, leaving behind only the πelectrons in the unhybridized 2p orbital. A very similar type of hybridization is experienced by the nitrogen atom in the azomethine group. Traditional phosphine complexes of nickel, palladium, and platinum, particularly those of palladium, have played an extremely important role in the development of homogeneous catalysis. Schiff base complexes as catalysts have been studied for various organic transformations such as oxidation, epoxidation, reduction, coupling reactions, polymerization reactions, hydroformylations, and many more.

**Keywords:** Schiff base metal-complexes, homogenous catalysis, oxidation, C-C coupling, epoxidation
