Intramolecular interaction effects and the structure of N2OS and N2O2: An Ab initio study

Abstract

AbstractAn ab initio study of ONNS with full geometry optimization has been carried out to corroborate the presence of an interaction between the terminal atoms in this type of structure, which, in ONNO, apparently stabilizes the cis conformer. Using the unscaled 4–31G basis set with a full set of d functions on the sulfur, there is a potential minimun at the trans but not the cis geometry. A gauche conformer with a torsional angle of 77.2° is the most stable. With N2O2 this basis set gives potential minima at both the cis and trans geometries, but the trans conformer is slightly more stable, contrary to experiment and the results of (7,3) basis‐set calculations reported in the literature in which Gaussian lobe functions were employed. Using a (9,5) basis set there is no longer a potential minimum at the cis geometry, and a gauche structure is more stable than the cis conformer as in the case of N2OS with the less‐extended basis set. Force constants (harmonic and anharmonic), compliance constants, relaxed force constants, and interaction‐displacement coordinates for both molecules are compared for key structural elements.