Mixed-stack complexes of tetrathiafulvalene. The structures of the charge-transfer complexes of TTF with chloranil and fluoranil

Infrared Investigations of the Neutral-Ionic Phase Transition in TTF-CA and Its Dynamics

“…TTF-CA (300 K) [3] TTF-CA (40 K) [2] a (Å) Based on transport measurements, similar observations are reported [11]: The down and up turn of the conductivity at ambient pressure (see Figure 2b) becomes broader and shifts to higher temperatures. The conductivity increases exponentially as it does with the pressure.…”

“…In Figure 7, the room temperature diffractogram of TTF-CA crystals are compared with the one derived from the published structural data by Mayerle et al [3]. The simulation was performed with the visualization software Diamond which is capable of generating diffraction spectra from crystallographic data.…”

“…Thereby, they are shifted and rotated slightly towards each other, leading to a maximum overlap of the molecular orbitals. First studies on the crystal structure and the bond lengths of the C=C double bond of TTF and CA as well as the C=O bonds in CA reveal that the molecules are almost neutral at room temperature caused by a small charge transfer between TTF and CA [3] that can be attributed to the large intermolecular distance of 3.70 Å [2]. Indeed, infrared measurements show that the charge transfer is ρ = 0.2 e [4,5] at ambient conditions.…”

“…Table 1. Unit cell parameter TTF-CA for 300 K and 40 K. The data were taken from Mazerle et al and LeCointe et al [2,3].…”

Charge-transfer complex of 2,2',5,5'-tetrathiafulvalene and p-benzoquinone

“…Frontier orbital theory predicts that quinone compounds should favor segregated stacks when complexed with TTF because the LUMO orbitals of a quinone compound lack the inversion symmetry of the TTF HOMO orbitals (Torrance, Mayerle, Lee & Bechgaard, 1979). Mayerle and co-workers (Mayerle, Torrance & Crowley, 1979) crystallized both fluoranil (2,3,5,6-tetrafluoro-l,4-benzoquinone) and chloranil (2,3,5,6-tetrachloro-l,4-benzoquinone) with TTF, expecting TTF-fluoranil (2) and TTFchloranil (3), Fig. 1, to crystallize in segregated stacks as a result of the mismatched orbital inversion symmetry of the components.…”