Nitrogen-15 Magnetic Resonance Spectroscopy. V. Oxygen-Nitrogen Compounds

The ^(15)N chemical shifts of a series of oxygen-nitrogen compounds have been found to vary over a range of 576 p.p.m. Since the calculated range of the diamagnetic contribution is only 80 p.p.m., the paramagnetic term must dominate. An observed correlation between the ^(16)N chemical shifts and the energy of the n → π* transitions substantiates this interpretation experimentally. For compounds such as nitric acid, which lack nonbonding electrons on nitrogen, contributions to the mean electronic excitation energy from nonbonding oxygen electrons may be important.