Theoretical Investigation of 4-Methyl-4H-1,2,4-triazole-3-thiol and Its Mononuclear and Dinuclear Palladium(II) Complexes; Molecular Structure, NBO Analysis, FT-IR and UV-Vis Spectroscopy

In this research, the characterization of complexes [Pd(aemptrz)Cl2] (1), [Pd2(μ- mptrz)2(mptrz)2(en)].CH3OH (2) [Pd2(μ-mptrz)4] (3) and [Pd2(μ-mptrz)2(mptrz)2(en)] (4) (where aemptrz is 1‐(1‐(λ2‐azanyl)ethyl)‐4‐methyl‐5‐(λ1‐sulfanyl)‐4H‐1λ4,2,4‐triazole, en is ethylene diamine and Hmptrz is 4-methyl-4H-1,2,4-triazole-3-thiol) were carried out by Density Functional Theory (DFT) calculations. Structural, electronics and molecular properties (such as bond distances, bond angles, energies of highest occupied molecular orbital (EHOMO), the lowest unoccupied molecular orbital (ELUMO), the energy gap (ΔE), chemical hardness η, the dipole moment μ and Natural bond orbital (NBO) analysis of compounds) have been investigated using density functional theory at two different functional methods (B3LYP and M06). Moreover, electronic structures of all complexes via NBO calculation show that Pd-N and Pd-S bonds are made of delocalization of occupancies from lone pair (LP) orbital of N, S atoms to the palladium atom. The FT-IR spectroscopy analysis and electronic spectra were calculated using B3LYP/TZVP basis set and compared with the experimental values. Furthermore calculation of vibrational spectra are also allocated based on the potential energy distribution (PED) using the VEDA 4 program. The electronic spectra were calculated using DFT and time dependent density functional theory (TD-DFT) methods.