Vibrationally resolved emission of thiophosgene dimer

During a study of thiophosgene electronic spectra, Fujiwara and co-workers observed a broad electronic transition peaked at 37 000 cm−1, attributed to thiophosgene dimer. Our dispersed fluorescence spectra of a thiophosgene molecular beam excited at 36 000 cm−1 reveal several vibrational modes too low in frequency for thiophosgene. We assign them to modes of thiophosgene dimer or their combination bands. MP2 calculations support the vibrational assignment. TD-DFT, CASSCF, and coupled cluster calculations suggest that the bright electronic state of thiophosgene dimer is the B2u symmetry fifth excited singlet state. Two additional transitions are assigned to a thiophosgene synthesis impurity, trichloromethanesulfenyl chloride.