(¹⁷O) Oxygen NMR

Oxygen has one naturally occurring NMR active nucleus, ¹⁷O. It has a spin of 5/2 and is therefore quadrupolar, yielding broad signals even for the smallest of molecules that become too broad to observe in a high resolution spectrometer even for medium sized molecules. The isotope ¹⁷O has a very low natural abundance of 0.038% combined with a relatively low receptivity and so is only observable for high concentrations (at least molar) or when enriched (very expensive, currently over $1000/mL of H₂¹⁷O, never mind anything more complicated). ¹⁷O has a very wide chemical shift range which for small molecules partially compensates for its broad signals. Each type of signal has a characteristic chemical shift range (figs. 1, 2).

Fig. 1. Chemical shift ranges for ¹⁷O NMR

Fig. 2. ¹⁷O-NMR spectrum of D₂O (peak on the left) and CD₃OD (right)

Properties of ¹⁷O

(Click here for explanation)

Safety note

Some of the materials mentioned here are very dangerous. Ask a qualified chemist for advice before handling them. Qualified chemists should check the relevant safety literature before handling or giving advice about unfamiliar substances. NMR solvents are toxic and most are flammable. Specifically, D₂O is toxic.