مطالعه تئوريکی پايداری توتومرهای تيوسمی¬کاربازون¬ها

In the first part of this study by using an Ab initio theory method and 6-31G** basis set (HF/6-31G**) and Density functional theory method with 6-311++G** basis set (B3LYP/6-311++G**), some factors such as zero point energy ,polarizability,hardness and electrophilicity are calculated for investigation of stability of different thiosemicarbazon tautomers. It is found that zero point energy and polarizability factors by using Ab initio theory method with 6-31G** basis set (HF/6-31G**) are the best for characterization of stability of tautomeric forms of thiol and thion. thion thiol In the other part stability of A(E-E) and B(E-Z) forms(configuration in relatin to the thio amid and the imino groupsrespectively) investigated by some factors such as zero point energy ,polarizability,hardness and electrophilicity ; in which revealed that zero point energy is the best factor for characterization of stability A(E-E) and B(E-Z) forms. At the end, charge and fukui of S, N, N, N atomes are calculated it is found that the reaction of thiosemicarbazon with transition metals in formation thiosemicarbazon complexes is controlled by frontier molecular orbitals but is not controlled by charge. we have investigated different factors which contribute in formation of four and five-membered rings of thiosemicarbazones complexes. According to the calculations, it is found that the actual driving force for such coordination mode of thiosemicarbazones, is the steric factor of the thiosemicarbazon ligand itself.