A number of tetrathiafulvalene (TTF) compounds with formal oxidation states, ρ, of TTF less than one (TTFρ+) were studied by resonance Raman spectroscopy. The ν3 frequencies are intermediate between those in TTF0 and the cation radical TTF+•. The ν3 frequency of TTF, TTFBr0.7, TTFI0.7, TTF(SCN)0.52, and TTF+ salts was used to demonstrate a linear relationship between ρ and ν3. This was used to determine ρ for transition-metal salts of TTF. TTFρ+ compounds were found to undergo laser-induced decomposition to form species which appear to contain TTF+. For the acceptor molecule tetracyanoquinodimethan (TCNQ), a similar relationship obtains between ρ and ν4 in derivatives containing TCNQ-. The resonance Raman spectrum of the conducting complex (TTF)(TCNQ) shows only one band each for ν3 and ν4 of TTF and TCNQ, respectively, from which the degree of charge transfer for both donor and acceptor is 0.58 ± 0.06. The total charge for each species is uniformly delocalized over all molecules in the segregated stacks in the solid.
ASJC Scopus subject areas
- General Engineering
- Physical and Theoretical Chemistry