关键词: electron charge density, electrostatic potential, molecular dipole moment and x-ray diffraction

Abstract: This work is devoted to the experimental determination of the electrostatic properties of the molecular 4-methyl-7- (salicylidene amino) coumarin (C₁₇H₁₃NC₃) using high resolution x-ray diffraction data. The experimental results are compared with those obtained theoretically from calculation type ab initio. The experimental investigation is carried out using the molecular electron charge density distribution based on the multipolar model of Hansen and Coppens. However the theoretical calculations are conducted by using the molecular orbital B3LYP method and the Hartree-Fock (HF) approximation with the basis set 6-31G (d,p) implemented in the Gaussian program. In addition to the structural analysis, the thermal agitation is also analyzed in terms of rigid blocks to ensure a better precision of the results. Subsequently, the electrostatic atomic and molecular properties such as the net charges, the molecular dipolar moment to highlight the nature of charge transfer existing within the molecule studied are derived. Moreover, the obtained electrostatic potential enables the localization of the electropositive and the electronegative parts of the investigated molecule. The present work reports in detail the obtained electrostatic properties of this biologically important molecule.

Key words: electron charge density, electrostatic potential, molecular dipole moment and x-ray diffraction