Absolute 15N shielding in dinitrogen trioxide: recalculation of the shielding tensors

A reanalysis of the absolute shielding tensors for the two nitrogens in N2O3 is made using results from recent calculations to fix the out-of-plane component of the tensor. The recalculated experimental values and theoretical values from density functional and multi-configurational methods are now in good agreement for the nitro nitrogen. Agreement for the nitroso nitrogen is not so good and suggests that multiconfigurational calculations with larger basis sets are required. Remeasurement of the microwave spectrum with greater resolution of the spin–rotation fine structure is needed to provide good experimental values for the absolute shielding tensor elements. Measurement of the 15N NMR spectrum of N2O3 would also be useful to obtain a more accurate value of the 15N chemical shifts.