In this thesis, the aliphatic pincer ligand, bis(2-(diphenylphosphino)ethyl)amine (a), and aromatic pincer ligand, N,N-bis(diphenylphosphine)-2,6-diamino-4-phenyl-1,3,5-triazine were synthesized. Then, the complexes of these ligands were synthesized using metal salts of nickel. These compounds were characterized by different techniques such as 31P NMR, 1H NMR, 13C NMR and UV-Vis spectroscopies. The crystal structures of [NiCl(T-Ph)]Cl, [NiI2(T-Ph)] and [NiCl(a)]Cl.EtOH were determined by X-ray crystallography from a single crystal. Also, the anticancer activity of the aliphatic pincer complex ([NiCl(a)]Cl) against MCF7 and HT29 cancer cells were investigated for the first time. The electrocatalytic activity of this complex was studied for reduction of hydrogen ion (H+) in organic solution. Electrochemical data showed that with a gradual increase in acid concentration, the current density increases and thus leads to the production of hydrogen. Also, the aliphatic pincer complex was immobilized on the SBA-15 using a suitable linker and characterized by FT-IR, ICP, XRD, UV-vis-DRS, SEM, TEM and thermal gravimetric analysis (TGA). These nanomaterials were used in the catalytic reduction of para-nitrophenol to para-aminophenol. In the other section, the catalytic activity of [NiCl(T-Ph)]Cl in C-S coupling reaction were investigated and monitoring with GC-MS, 1H NMR and 13C NMR analysis. In addition, [NiI2(T-Ph)] was used in the electrocatalytic reaction of hydrogen. Also, in this thesis, the kinetics and thermodynamics of one-step preparation of a ligand were investigated using theoretical calculations. Calculations showed that the preparation of this ligand does not require lithium phosphorus precursor and can be prepared without any change in the initial phosphorus precursor and only by optimizing the conditions of the a ligand.