The present work involves, new Schiff base of (E)-2-(((3-mercapto-5-(3,4,5-trimethoxyphenyl)-4H-1,2,4-triazol-4-yl)imino)methyl)phenol (L2) has been synthesized by condensation reaction of 4-amino-5-(3,4,5trimethoxy phenyl)-4H-1,2,4-triazole-3-thiol with 2-hydroxybenzaldehyde. The new Schiff base (L2) used as a ligand to synthesize a new complex with Co(II), Ni(II), Cu(II), Pd(II), and Cd(II) metal ions by 1:1 (Metal: ligand) ratio. New ligand and their complexes have been exanimated and confirmed by fourier-transform infrared (FT-IR), ultraviolet-visible (UV-visible), proton nuclear magnetic resonance (1HNMR), carbon13 nuclear magnetic resonance (13CNMR), microelement analysis (CHNS), thermal analysis (TG-DTA), atomic absorption flame (AAF), conductivity and magnetic susceptibility. The results obtained from spectra, elemental analyses and thermal analyses (TG-DTA) and compare by density functional theory (DFT) and TD-DFT calculations were screened for some selected complexes and the observed data indicated their stability and the expected chemical formula, palladium(II) were square planner geometry in [PdL2Cl] formula, whereas the copper(II) , cobalt (II), Nickel (II), and cadmium (II) were octahedral and tetrahedral geometry respectively in the formulas, [ML2(H2O)2Cl] and [CdL2Cl] , M=Cu, Ni and Co(II) ions.