14N NMR Studies on Cyclic Nitramines. Correlations of Chemical Shifts withNitrogen Partial Atomic Charge and Pi-Orbital Overlap

摘要

The 14N chemical shifts of nitro groups in the NMR spectra of cyclic nitramineshave been correlated with their electronic environment in the minimum energy conformers determined using AM1 semiempirical molecular orbital calculations. Both the Mulliken population derived atomic charge at the nitro nitrogen and the extent of Pi-orbital overlap influence the observed shifts. Equations useful for predicting the shifts of nitro groups bonded to either the imino group of cyclic guanidines or secondary amines and ureas in heterocycles have been derived and are discussed. (jg).