Suitable basis sets for accurate NMR chemical shift calculations: an application to in vivo studies of benzothiazole metabolites.

This paper describes atomic orbitals which have direct physical interpretation, i.e. Coulomb Sturmians and hydrogen-like orbitals. The radial nodes are shown to be essential in obtaining accurate nuclear shielding tensors for NMR work. The method is applied ab initio to chemical shifts for (15) N NMR, which can also be measured. This procedure is shown to be a useful tool in structure determination for benzothiazoles, some of which are used as pesticides and represent a challenging use of biodegradation. The measurements may be made in biological media, for which a rudimentary simulation is provided by including a few discrete solvent molecules.