Assignment of carbon‐13 NMR spectra and sign determination of long range carbon‐13—proton coupling constants with SPI

The application of selective population inversion (SPI) to the assignment of 13 C resonances and to the determination of the relative sign of 13 C 1 H coupling constants is demonstrated for 1‐phenyl‐1,2‐dibromo‐2‐nitroethane. A negative sign for the geminal C‐2H‐1 coupling constant has been determined from the 13 C spectra. The relationship between SPI and TSI is discussed.