Selenium-77 nuclear magnetic resonance in mono- and disubstituted benzo[b]selenophenes

The ⁷⁷Se chemical shifts of 79 mono- or disubstituted benzob]selenophenes are reported. The results in the 2- and 3-substituted derivatives closely parallel those previously obtained in the corresponding selenophenes. The measured parameters also correlate well with those measured in benzob]tellurophenes. The ¹²⁵Te and ⁷⁷Se chalcogen nuclei appear to be much more sensitive to substituent effects than the more classical nuclei. The effects of Cr(acac)₃, Eu(dpm)₃ and concentration on the ⁷⁷Se NMR spectra are briefly discussed.