Karplus relationships of the 2 J HNα and 3 J ΗΝβ couplings in organic azides

Density functional theory (DFT) and second-order polarization propagator approximation (SOPPA) computations in model organic azides revealed a Karplus-like dependence not only of the vicinal J coupling but also of the geminal J one, with the H-C-N N dihedral angle. Karplus equations were derived from the DFT computations on the isopropylazide model system. In light of these stablished relationships, natural abundance H- N couplings obtained for the azide group of the zidovudine antiviral helped to probe its conformation around the C-N bond as being of the synclinal type.