AbstractThe1H,13C and77Se chemical shifts have been measured for mononitrobenzo[b]selenophenes. For the homocyclic nuclei, the observed1H‐ and13C‐values calculated from the empirical increments of nitrobenzene. Anomalous effects are observed in the 2‐ and 3‐substituted derivatives and the nature of the SeNO2interactions in the former is discussed.77Se chemical shifts of the 4‐, 5‐ and 7‐nitro derivatives are approximately correlated with the CNDO calculated electron densities; they also compare well with those of selenoanisoles and other phenyl alkyl selenides. The chemical shifts are also compared with the corresponding values in other heterocycles containing a sel