HF and DFT calculations of the molecular structure of isomeric thiadiazoledioxides

The chemistry of thiadiazoles and their derivatives is of considerable inte rest in chemistry owing to their potential industrial applications as build ing blocks of conjugated conductive polymers. In this context, a detailed s tudy of isomeric thiadiazole dioxide molecules has been done using Hartree- Fock and local and nonlocal density functionals and optimizing the molecula r geometries by means of the gradient technique. A charge sensitivity analy sis of the studied molecules has been performed by resorting to density fun ctional theory, obtaining several sensitivity coefficients such as the mole cular energy, net atomic charges, global and local hardness, global and loc al softness and Fukui functions. With these results and the analysis of the dipole moments, the molecular electrostatic potentials and the total elect ron density maps, several conclusions have been inferred about the preferre d sites of chemical reaction of the studied compounds. The condensed Fukui functions are shown to be one of the best criteria for predicting chemical reactivity. (C) 2001 Elsevier Science B.V. All rights reserved.