Etude via la méthode DFT des complexes des métaux divalents (ni et zn ) avec l’hexamethylenetetramine

Abstract

This thesis presents reports on the theoretical study aiming at understanding the geometric structure, spectroscopic properties (FTIR and UV-visible) and nonlinear optical properties of two divalent metal complexes ([Ni(hmta)2(H2O)2] and [Zn(hmta)2(H2O)2] ) in the gas phase. This work is based exclusively on quantum calculation based mainly on the density functional theory DFT and its time-dependent extension TD-DFT. It should be noted that the reliability of the DFT approach was verified by obtaining the geometry, IR vibration modes and parameters of the nonlinear optical properties of these complexes. The DFT approach was verified by obtaining the excitation energies and oscillator strengths for different complexes ions. These calculation methods have been successfully used for the determination of the vibration spectra and electronic spectra of divalent metal complexes with hmta. The results obtained, which are consistent with the literature review, allow to briefly explain the respective square-planar and tetrahedral geometries of the complexes ions [Ni(hmta)2(H2O)2] and [Zn(hmta)2(H2O)2] , complex ions to compare the parameters such as the dipole moment (μ), isotropic polarizability (α) and first-order hyperpolarizability (β) parameters with those of urea and to present the different electronic transitions observed in the two complexes based on the contributions and the character of the molecular orbitals, particularly the frontier orbitals (HOMO-LUMO) and on the nature of the charge transfer between the metals and the ligand.