DETERMINATION DE LA DISTRIBUTION DE LA DENSITE ELECTRONIQUE DANS UN COMPOSE ORGANIQUE

Abstract

The work presented in the context of this thesis concerns the determination of the distribution of electron density of compound chemical formula C8H9NOS from a spectrum of high-resolution X-ray diffraction on single crystal of this compound, this determination requires first a record of high quality diffraction spectrum of materials studied, followed by appropriate treatment of these intensities. we used the formalism of blessing for reducing these intensities taking into account the different experimental errors that may affect measurements, ultimately provide the best structure factors that were used in the analysis of electron density that work essentially consists of four distinct parts: The first part devoted to the study of the nature of X R and the production process and the interaction of radiation with matter (Bragg law), was cited as the deferential theoretical calculation methods such as DFT (-HF), Part II presents the experimental device and the steps we have begun to record and cover the spectrum of X-ray diffraction for solving and refinement of crystal structure, The third part of the determination of the crystal structure which involves two steps: the resolution and the structure refinement and structural analysis of the molecule. during the resolution and the structure refinement were used respectively the following two programs [Shels] and [SHELXL] respectively, the resolution of the structure leads to coordinate positions xj, yj, zj, but the most interesting for we chemists is the arrangement of atoms with each other, for this purpose, we describe the structure of these bond lengths and valence angles and torsion angles, the last part reserved for analysis of distribution of electron density on the molecule different plans, we use the structural parameters, positional and thermal refinement obtained to draw the maps of electron density in the plane of the molecule C8H9NOS.