¹³C and ¹⁵N NMR spectra of high‐energy polyazidocyanopyridines

Abstract

C and N NMR spectra of high-energy 2,4,6-triazidopyridine-3,5-dicarbonitrile, 2,3,5,6-tetraazidopyridine-4-carbonitrile and 3,4,5,6-tetraazidopyridine-2-carbonitrile are reported. The assignment of signals in the spectra was performed on the basis of density functional theory calculations. The molecular geometries were optimized using the M06-2X functional with the 6-311+G(d,p) basis set. The magnetic shielding tensors were calculated by the gauge-independent atomic orbital method with the Tao-Perdew-Staroverov-Scuseria hybrid functional known as TPSSh. In all the calculations, a polarizable continuum model was used to simulate solvent effects. This approach provided accurate predictions of the C and N chemical shifts for all the three compounds despite complications arising due to non-coplanar arrangement of the azido groups in the molecules. It was found that the N chemical shifts of the N atoms in the azido groups of 2,4,6-triazidopyridines correlate with the C chemical shifts of the carbon atoms attached to these azido groups. Copyright © 2016 John Wiley& Sons, Ltd.

Unravelling the Structure of Chemisorbed CO2 Species in Mesoporous Aminosilicas: A Critical Survey

“…Overall, there is a systematic but small positive shift in the calculated values compared to the experimental ones. Such cases occasionally occur when using DFT methods to calculate 15 N NMR CSs [51][52][53] , and were also observed in the case of the aqueous alkylamines considered here to determine a reference root-mean-square error (see computational details and calculated values in Table S25).…”