Preparation, Structure Determination, and Electrochemical Properties of 4,5‐Dialkylbenzo[1,2‐d:4,5‐d']bis[1,2,3]triselenoles and Their Singlet and Triplet‐State Dications.

4,8‐Dialkylbenzo[1,2‐d:4,5‐d']bis[1,2,3]triselenoles [alkyl=Et, Bu, and Oc (C8H17)] were first prepared and treated with concentrated sulfuric acid‐d2 to generate benzobistriselenole dications, which were determined by NMR spectroscopy. The oxidation of dioctylbenzobistriselenole with three equivalents of single‐electron oxidizing reagent (NOSbF6) produced the corresponding dication.2SbF6−, and the salt was isolated into a stable form. The ESR spectra of the dications measured in concentrated sulfuric acid in the range of room temperature and −196 °C were observed as split peaks similar to that of solid state dication.2SbF6−. Magnetic susceptibility of the dication.2SbF6− was determined by a superconducting quantum interference device (SQUID) magnetometer, which showed the salt is diamagnetic. The optimized structures and the total energy of the singlet‐ and triplet‐state benzobistriselenole dications were calculated using the density functional theory (DFT) method at the B3LYP6‐311G**(d,p) level. The results revealed that the structures of the singlet‐ and triplet‐state dications calculated have a completely planar forms and the triplet‐state dication is slightly more stable than the singlet‐state one in acetonitrile using a polarizable continuum model (PCM). [ABSTRACT FROM AUTHOR]