Charge-transfer complexes of arylthiotetrathiafulvalenes and TCNQF4: their structural diversity and electronic states

Abstract

A series of charge-transfer (CT) complexes have been prepared via diffusion and evaporation methods comprising arylthio-substituted tetrathiafulvalene (Ar-S-TTF) derivatives 1–5 and TCNQF4. Crystallographic studies revealed the diverse crystal packing of the CT complexes, which is related to their flexible structure and the planar central cores of the Ar-S-TTF. The complexes could be divided into three systems according to the packing similarities and dissimilarities of Ar-S-TTF (donor, D) and TCNQF4 (acceptor, A), namely Class 1 (D on D and A on A segregated stacking), Class 2 ((–A–D–)n mixed stacking) and Class 3 (–D–D–D–D– and A, A stacks with each other in edge-to-face interactions between cations and anions). The presence of multiple intermolecular interactions promotes the formation of various stacking structures. There are two factors affecting the packing structures and compositions of the CT complexes: (1) the aryl groups thereon of Ar-S-TTF; and (2) the expanded π-conjugated system.