Das UV/VIS-Absorptionsspektrum des 9.9′-Dianthryl-disulfids / The UV /VIS Absorption Spectrum of 9,9′-Dianthryl disulphide

Abstract 9,9′-Dianthryl disulphide is the first example studied for a diaryl disulphide whose uv/vis absorption spectrum exhibits a distinct vibrational structure whereas the formerly investigated spectra of diphenyl disulphide and the isomeric dinaphthyl disulphides are characterized by the complete lack of vibrational structure. Different interpretations have been given in the literature for this particular property of the diphenyl disulphide and dinaphthyl disulphide spectra. The long wave-length region of the dianthryl disulphide spectrum is interpreted with the assumption of three electronic transitions. Two of them are localized in the anthracene or dithio anthracene chromophore, respectively, whereas the third transition is assumed to be non-localized including the whole system with the S-S bridge acting as a conjugative (butadienoid) link. This assignment is consistent with a pπ-model without pπ/dπ-participation in agreement with results of photoelectron spectral investigations on disulphides reported in the literature.