NICS Rate Evaluation for Some Substituted Aromatic Rings : B3LYP Study

The NICS-rate indicator is introduced as a new aromaticity scale. The attendance of the maximum/minimum in the NICS-rate curve of a molecule shows to aromaticity/antiaromaticity of the system. In this research the optimized structure of six and four member conjugated rings were calculated by B₃LYP method, 6-311++G**(d,p) basis sets, and Gaussian03w program. After optimization the structure of rings, the NMR or the magnetic field above the rings from zero to about 3.0 angstrom was calculated by locating the Ghost atoms in the each place (NICS). The results are very interesting and show that the NICS-rate of six member rings are increases as the number of F , NO₂ and CF₃ atoms increases. . In the same trend increasing the F and CF₃ number attached to four rings decreases the antiaromaticity of them.

کلیدواژه ها:

Aromaticity ، NICS ، NICS-rate