A more reliable oxygen-17 absolute chemical shielding scale

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Abstract
For the first time, oxygen‐17 chemical shifts together with experimental details are reported for CO, CO2, OCS, N2O, and OF2. An absolute 17O shielding scale, based on a recent redetermination of the 17O spin‐rotation constant in C 17O is proposed: σ (C 17O)=−42.3±17.2 ppm. Absolute shielding constants derived from 17O NMR chemical shifts are compared with those calculated from recent molecular orbital studies. Also scalar coupling constants involving 17O are reported for OF2 and CO. In OF2, J(F,O)=300±30 Hz; in carbon monoxide, J(O,C) is less than 5 Hz.