Chloromethane chemical shifts

If more than one electron-withdrawing group is present, the deshielding effects are nearly (but not quite) additive. In the chloromethanes (Table 13-2), the addition of the first chlorine atom causes a shift to 8 3.0, the second chlorine shifts the absorption further to 8 5.3, and the third chlorine moves the chemical shift to 8 7.2 for chloroform. The chemical shift difference is about 2 to 3 ppm each time another chlorine atom is added, but each additional chlorine moves the peak slightly less than the previous one did. 

The chloromethanes constitute a suitable series for testing theories of chlorine chemical shifts. We have performed CNDO/2 calculations of the molecules in this series and calculated the chlorine... 

Following are structural formulas, dipole moments, and H-NMR chemical shifts for acetonitrile, fluoromethane, and chloromethane. 

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