13 C - NMR chemical shifts in substituted benzenes w. ADF & NBO¶
Learn how to analyse the effects of NH2 and NO2 substituents in ortho-, meta-, and para-positions on chemical NMR shifts of aromatic carbon atoms forming a benzene ring. These well known shifts in aromatic systems are commonly believed to originate from a depletion or accumulation of electrons in the π-orbitals at these atoms.
To examine this claim by means of NMR calculations with ADF and NBO/NLMO analysis tools of the AMS modeling suite, check out the complete tutorial Analysis of NMR parameters with Localized Molecular Orbitals.
The tutorial thereby loosely follows the publication:
R. V. Viesser, L. C. Ducati, C. F. Tormena and J. Autschbach The unexpected roles of σ and π orbitals in electron donor and acceptor group effects on the 13C NMR chemical shifts in substituted benzenes, Chem. Sci. Phys. 8, 6570-6576 (2017).