σ-Delocalization between Non-bonded Selenium Atoms on Multiply Se-substituted Benzenes

Systematic studies on the delocalization arising from lone-pair interactions of non-bonded selenium atoms in multiply selenium-substituted benzenes are demonstrated. The electrochemical measurement and quantum-chemical calculations reveal that the first oxidation potentials of the compounds shift to a lower voltage as the number of adjacent selenium atoms increases from unity to six. The resulting steric hindrance forces the selenium functionalities to bring about σ-delocalization derived from interactions between lone-pair electrons of non-bonded selenium atoms.