The structure of 2‐carboxyphenyl methyl selenoxide, its sodium salt and related compounds in solution, studied by ¹H, ¹³C and ⁷⁷Se NMR

Abstract 1 H, 13 C and 77 Se NMR spectra of 2‐carboxyphenyl methyl selenoxides, 2‐carboxyphenyl phenyl selenoxides, their sodium salts and related compounds have been measured to determine their structures in solution. The 77 Se NMR chemical shifts and the J ( 77 Se, 13 C) values were found to be particularly useful in distinguishing between selenuranes and selenoxides. The downfield shifts of 286‐536 and 587‐667 ppm from selenoanisoles are characteristic of the corresponding selenuranes and selenoxides, respectively. The couplings were 61‐65 and 77‐81 Hz for the selenuranes and selenoxides, respectively. The effects of salt formation on the NMR parameters are also discussed. The results show that the carboxylic acids have the cyclic selenurane structure, whereas the salts are acyclic selenoxides.