Some Molecular Properties and Reaction Mechanism of Synthesized Isatin Thiosemicarbazone and Its Zinc(II) and Nickel(II) Complexes

The aim of this study is to 1H-Indole-2,3-dione 3-[N-(4-fluorophenyl)-thiosemicarbazone and its zinc(II) and nickel(II) complexes. The structures of the synthesized compounds were confirmed by spectral data and elemental analysis. They were optimized by B3LYP theory with different basis sets. The optimized structures were compared with the experimental values. TD-DFT calculations Original Research Article Kandemirli et al.; IRJPAC, 9(1): 1-16, 2015; Article no.IRJPAC.17626 2 on electronic absorption spectra in gas phase and DMSO were performed to determine the electronic transitions of the compounds. The Frontier Molecular Orbital analysis were also done in order to identify the charge transfer interaction that takes place between the molecular orbitals. Reaction mechanism of 1H-indole-2,3-dione-3-(N-4-fluorophenyl thiosemicarbazone) molecules were also studied.

The precipitated product was filtered, purified and dried. Orange solid product was obtained.
Gaussian assumes electronic distribution as a function of the molecular geometry (Born-Oppenheimer approximation). The vibrational frequency calculations are required for understanding whether it has been obtained from a stable minimum structure. Negative imaginary frequencies were found in calculations for TS1 and TS2 (the negative frequencies for TS1 and TS2 are 315 and 1743 cm -1 ).
As well as the presence of a negative frequency defining the minima connected through the transition state is required. We chose the intrinsic reaction coordinate (IRC), and defined as the minimum energy reaction pathway (MERP) in mass-weighted Cartesian coordinates that between the transition state of a reaction and its reactants and products (Fig. 11). The reactivity of a molecule is closely related to the highest occupied molecular orbital-HOMO and the lowest empty molecular orbital -LUMO and the parameters such as hardness, softness can be calculated using HOMO and LUMO energies. The higher value of E HOMO means its ability to donate electrons to appropriate
The lack of N-H31 chemical shift belong to thiosemicarbazone group for Zn[(I4FPTH) 2 ] complex which is observed for I4FPTH2 ligand indicates that deprotonation take place during complexation reaction. Oscillator strengths (f) and excitation energies (eV) for UV spectra values of all studied compounds were summarized in Table 6 (Table 6).

CONCLUSION
Results of quantum chemical calculations of 1Hindole 2,3-dione-3-(N-4-fluorophenyl thiosemicarbazone and its Zinc (II) and Nickel (II) complexes showed that HOMO energies and polarizibility of complexes are found higher than those ligand. In addition to quantum chemical calculations, experimental values indicates that Zn(II) complex of ligand coordinates via C=N and C=S of its ligand while Ni(II) complex coordinates via C=O C=N and C=S. The results of 13 C NMR calculation with B3LYP/6-311G(2d,2p) method were obtained most sensitive in the all methods.