Efficiency of the MNDO-PM3 method to describe the geometric and electronicstructure of 1,2-dithiole-3-thiones and 1,2-dithiole-3-ones

In order to validate the PM3 semi-empirical calculation method for the stud y of electronic and geometric structures of a dithiolethiones and a dithiol ones series, we compared: the experimental dipole moments of 22 dithiolethiones and 10 dithiolones wi th those calculated by PM3, the experimental bond lengths determined by X-ray of 5 dithiolethiones with the calculated ones. Finally, we used more elaborate calculation methods such as nb initio HF/6- 31G* and density functional theory (DFT) B3LYP in order to confirm the net charge distributions calculated by the PM3 method. Results are satisfactory PM3 calculations provide a simple, efficient and r apid methodology study of the structure of a large number of molecules belo nging to the same series.