Dialkyl dichalcogen cations

One electron oxidation of dialkyl diselenides and ditellurides is achieved with NO+CF3SO3-. According to ab initio calculations the radical cations have a trans stucture. In the solid state they dimerize to rectangular units [R - Te](4)(2+) and [R - Se](4)(2+). The long Se center dot center dot center dot Se and Te center dot center dot center dot Te bond is obviously due to a pi(*) - pi(*) interaction.