In this thesis, two mononuclear polyPyridyl complexes of nickel(II), [Ni(tptz)(MeOH)Cl 2 ] and [Ni(tptz) 2 ](PF 6 ) 2 ·CH 3 CN, (where tptz ligand 2,4,6-tris(2-Pyridyl)-1,3,5-triazine) have been prepared and characterized by elemental analysis, FT-IR, UV-Vis and 1H NMR spectroscopies. Solid state structures of both complexes were determined by single crystal X-ray crystallography. The coordination geometry around the six-coordinated Ni(II) center in [Ni(tptz)(MeOH)Cl 2 ] complex is a distorted octahedron and tptz as a tridentate ligand occupies three binding sites. The FT-IR spectrum of this complex shows the shift of C = N and C = C bonds to the higher frequencies compared to free tptz ligand. Based on the ORTEP diagram of [Ni(tptz) 2 ](PF 6 ) 2 ·CH 3 CN complex, two tridentate tptz ligands, are coordinated to the metal center through their N atoms in a mutually perpendicular fashionand and provide a distorted octahedral geometry around Nickel. The shortening of the Ni-N triazine bonds compared to the Ni-N pyridyl bonds can be related to the stronger ? - accepting properties of the triazine ring. ORTEP drawing and elemental analysis of this complex confirms the presence of an acetonitrile molecule in the crystal structure. The lattice structure is further stabilized by a network of weak hydrogen bonds between the H atoms of the pyridyl rings and the F atoms of PF 6 – anions. The protonated form of Tptz, [tptzH 2 ](PF 6 ) 2 ·H 2 O, has been prepared and characterized by FT-IR, UV-Vis, 1 H NMR and fluorescence spectroscopies. The solid state structure of this compound were determined by single crystal X-ray crystallography and by computational methods using Moltran and gaussian softwares performed by DFT calculations using B3LYP/6-311+ G ** level of theory. According to the ORTEP diagram of this compound, only two nitrogen atoms of the total six nitrogen atoms of tptz ligand are protonated. Also, there is a molecule of water as the crystallized solvent in the crystal structure of the compound. As understood from the packing pattern, the lattice structure is further stabilized by a network of non-covalent interactions of the hydrogen bonds. By using of B3LYP/6-311 G ** method, FT-IR spectra of tptz and tptzH + and tptzH 2 2+ configurations were calculated that showed there is a very good agreement between experimental and calculated results. Furthermore, 1 H NMR spectrum of tptzH 2 2+ N36N16 configuration is calculated using the B3LYP/6-311 G (2d, P) than TMS.