Vibrational Spectra of Organic Conductors. Charge Transfer Salts of TTF with Substituted p -Benzoquinones

Abstract

Charge transfer salts of tetrathiafulvalen (TTF) with five substituted p-benzoquinones (fluoranil, chloranil, bromanil, iodanil, and 2,3-dichloro-5,6-dicyano-p-benzoquinone) were prepared by diffusion and cooling methods. IR, Raman, and electronic spectra of these salts measured at room temperature showed that all except fluoranil salt formed two crystal phases, i.e., the diffusion and the cooling methods gave a mixed-valent and a monovalent ionic phases respectively. The degrees of charge transfer (ρ) of the mixed-valent salts were estimated from the Raman frequencies of ag ν3 of TTF, and nearly equal values (ca. 0.7) were obtained for all of them.