Authors: Vadim V Nazarenko
DENSITY FUNCTIONAL THEORY (DFT) INVESTIGATION OF RSNNSR SYSTEMS The structural variations and stabilities of RSNNSR systems were studied using the hybrid density functional theory (B3LYP) at various basis set levels. Computational methodology was based on the locally dense basis set approach (LDBS) that assigns various levels of the basis sets accordingly to the previously calibrated results that could be correlated to the experimental data. The present study investigated the effect of the substituents (R) on the structure and the stabilities of RSNNSR systems. There were totally ten systems studied where R: H, CH3, CF3, tert-Butyl, C6H6, p-NO2C6H6 , p-CH3OC6H6. The calculations revealed that the stability of the S-N bond is enhanced if there is a combination of the electron-releasing effect and the electron-withdrawing one that creates a push-pull effect (captodative effect) in the system. An increase of a positive charge on one of the sulfur atoms and a negative charge on the adjacent nitrogen atom increases delocalization of one the S’s lone pairs that creates a conjugation with the neighboring N atom and the β carbons through 2pπ-3pπ interactions. The push-pull effect also influenced structural characteristics of the systems. One of the most notable ones is the variation of the NSCC dihedral angle in some of our systems from 89° to 21°
Comments: 99 Pages.
[v1] 2013-02-11 22:15:01
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