Résumé:
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.
