Discussion Our results fully confirm the existence of the deshielding regions shown in Figure 1 that are predicted on the basis of the magnetic anisotropy of the carbon-carbon triple bond. 16-18 These results not only demonstrate that acetylenic deshielding exists but also show that the magnitude of this deshielding, as expected, falls off with distance. For example, as a consequence of the rapid rotation of the C-4 methyl group in acetylene 2, each of the three ...
