Crystal structures of two charge-transfer com-plexes of benzo[1,2-c:3,4-c':5,6-c'']tri-thio-phene (D 3h -BTT).

Benzo[1,2-c:3,4-c':5,6-c'']tri-thio-phene (D 3h -BTT) is an easily prepared electron donor that readily forms charge-transfer complexes with organic acceptors. We report here two crystal structures of its charge-transfer complexes with 7,7,8,8-tetra-cyano-quinodi-methane (TCNQ) and buckminsterfullerene (C60). The D 3h -BTT·TCNQ complex, C12H6S3·C12H4N4, crystallizes with mixed layers of donors and acceptors, with an estimated degree of charge transfer at 0.09 e. In the D 3h -BTT·C60·toluene complex, C12H6S3·C60·C7H8, the central ring of BTT is 'squeezed' by the C60 mol-ecules from both faces. However, the degree of charge transfer is low. The C60 unit is disordered over two sites in a 0.766 (3):0.234 (3) ratio and was refined as a two-component inversion twin. © Qin et al. 2019.