14N nuclear quadrupole resonance and ab initio MO study of organic azides

Abstract:

An ab inito SCF-MO calculation of the electric field gradient (EFG) using a double zeta basis set with polarization is reported for N<inf>3</inf> ^-, HN<inf>3</inf> NCN<inf>3</inf>, and H<inf>3</inf>CN<inf>3</inf>. A similar calculation using a Dunning set with polarization is also reported for N<inf>3</inf>^-, HN<inf>3</inf>, and H<inf>3</inf>CN<inf>3</inf>. Excellent correlation was found between the calculated and the components obtained from gas phase microwave data. The calculation showed that the terminal N atom had a positive nuclear quadrupole coupling constant and its pincipal z axis was found to be perpendicular to the NNN direction in substituted azides. The changes in the charge distribution of HN<inf>3</inf> and NCN<inf>3</inf> obtained from the analysis of the atomic multipoles was shown to be in general agreement with the variations found in the N EFG components calculated for these azides. The ¹⁴N nuclear quadrupole resonance frequencies of the terminal and the first N atom of the azide group have been measured at 77 K for phenyl, benzyl, triphenylmethane, and tosyl azide. An analysis based on the Townes and Dailey approach of the measured NQR data showed that the terminal N atom have lost more σ than π orbital population. A similar analysis for the first N atom of azides showed strong inductive and resonance interactions with the substituents. © 1987 American Institute of Physics.

Año de publicación:

1987

Keywords:

Fuente:

scopus