Spectroscopic study of solid BDNT and its monocation and dication salts

Abstract

The polarized reflection spectra of BDNT, BDNT-PF₆ and BDNT-(PF₆)₂ have been measured on several crystal faces of the single crystals and compared with the solution spectra of BDNT, BDNT⁺ and BDNT²⁺. The spectra of the BDNT crystals have been successfully interpreted in terms of the theory of directional dispersion. Based on this interpretation, the electronic spectra of BDNT, BDNT⁺ and BDNT²⁺ have been reasonably assigned to the electronic transitions expected from the molecular orbital calculations. We found a disproportionation reaction in the acetonitrile solution of m-BDNT-PF₆, which means that the dication state is close to the monocation state. This is in accord with the low excitation energy (3.5 × 10³ cm^–1) of the charge-transfer band in m-BDNT-PF₆. The vibrational bands of BDNT, m-BDNT-PF₆ and BDNT-(PF₆)₂ are presented and discussed.