Conformation, structure et spectroscopie du (4,4'-diacetyl) diphenylselenium (C 16 H14O2Se).

Abstract

In this work it is presented in a continuation of work undertaken in our laboratory on poly benzenes substituted by halogens and méthyles to determine their structures and more particularly the location of the protons of methyl group. The crystal structure of p, p'-diacétyldiphénylsélénium (C16 H14O2Se) was determined at room temperature by X-ray diffraction The crystal is monoclinic with space group P21 / a and Z = 4. The refinement of the molecule led to the program CRYSTALS revealed no disorder. The contact distances correspond to inter molecular interactions of van der Waals type. Entities A and B phenyl-acetyl although they are equivalent and symmetrical position relative to the central Se atom of p, p'- diacétyldiphénylsélénium are some differences in angles and link lengths of the crystalline structure. -We used the chain of programs GAUSSIAN03 based on two functional exchange-correlation B3LYP and MPW1PW91 and a sufficiently extended to products suitable for organic produce results very close to those obtained experimentally from the diffraction of x-ray. -A good agreement in calculating angles crossover from quantum mechanics using the functional MPW1PW91 and bases 6-311G and LANL2DZ is found compared to experiment (0.78% [6-311G] and 0.72% [ LANL2DZ]). -The functional B3LYP and basis LANL2DZ compared to the experience also gave a good agreement of 0.80% in the calculation of angles liaison. -The molecular conformation of the dibromonitrotoluene molecule (C16H14O2 SE), was calculated by DFT method with the functional B3LYP, MPW1PW91 by the different bases Lanl2DZ, 6-311 respectively. -The agreement with experiment for link lengths using the functional MPW1PW91 is 4.3% [LANL2DZ] and 3.8% [6-311G]. -The allocation of different modes of vibration of the molecule is shown from the frequencies obtained experimentally and theoretical calculations some differences that can improve handling at low temperatures.