The synthesis and spectroscopic examination of telluronium salts based on the 1-organo-3,4-benzo-1-telluracyclopentane cation

The syntheses of a new range of telluronium salts based on the 1-organo-3,4-benzo-1-telluracyclopentane cation are reported (C₈H₈TeRX: R  CH₃, CH₂CH₃, X  I; R  CH₃, X  PhCOO; R  CH₃, X  ClO₄; R  CH₃, X  BPh₄; R  Ph, X  BPh₄; R  CH₂Ph, CH₂CHCH₂, CH₂COPh, X  Br.) Solution studies using ¹H, ¹³C and ¹²⁵Te NMR spectroscopy in conjunction with conductivity and molecular weight measurements show the salts to be associated via weak “ionic” bonds in solvents of lower polarity such as chloroform but to be more ionic and strongly solvated in DMSO. Solvents such as DMF provide an intermediate and more complex situation.Mass spectra indicate that association can extend to the gas phase and some novel features in the spectra are discussed. Infrared studies indicate polymorphism for 1-methyl-3,4-benzo-1-telluracyclopentane perchlorate with one form containing perchlorate ions interacting with tellurium.