THEORETICAL-STUDIES ON THE STRUCTURE AND ELECTRONIC-PROPERTIES OF 3-(4-TOLYL)SYDNONE

The structure of 3-(4-tolyl)sydnone has been calculated using the semi empirical MNDO, AM1 and PM3 methods and at the ab initio STO-3G, 3-21G and 6-31G* levels and the resulting geometries compared and contrast ed with the well resolved crystal structure. While the geometry of the phenyl ring is well reproduced particularly by the ah initio methods, none of the methods give a satisfactory account of the geometry of th e sydnone ring. The calculated charge distributions of atoms in the he terocylic ring vary considerably depending on both the molecular orbit al method used and the analysis technique adopted. The calculated dipo le moments are generally overestimated with the best results obtained with the MNDO method for the semiempirical procedures and the STO-3G b asis set for the ah initio methods.