Crystal structures of two charge–transfer complexes of benzo[1,2-c:3,4-c′:5,6-c′′]trithiophene (D 3h -BTT)

Abstract

Benzo[1,2-c:3,4-c′:5,6-c′′]trithiophene (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-tetracyanoquinodimethane (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 molecules 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.