Vibrational modes of the anthracene—tetrachlorophthalic anhydride charge-transfer complex

Abstract

Raman and i.r. studies of the anthracene—tetrachlorophthalic anhydride charge-transfer complex have been carried out. Five lattice modes are identified in the low-frequency Raman spectra. The 21 cm −1 lattice band is tentatively assigned to the librational vibration of the donor and acceptor molecules along their stacking axis. The intramolecular modes are assigned on the basis of the free-molecule symmetries D 2 h and C 2ν for anthracene and tetrachlorophthalic anhydride, respectively. The intramolecular frequencies do not change significantly on complexation. This suggests that the molecular symmetry and the force constants between interacting molecules are not greatly affected by the formation of the complex.