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 3 J H–C–Nα–Nβ coupling but also of the geminal 2 J H–C–Nα one, with the H–C–N α N β dihedral angle. Karplus equations were derived from the DFT computations on the isopropylazide model system. In light of these stablished relationships, natural abundance 1 H– 15 N couplings obtained for the azide group of the zidovudine antiviral helped to probe its conformation around the C–N α bond as being of the synclinal type.