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

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 (C(60)). The D (3h)-BTT·TCNQ complex, C(12)H(6)S(3)·C(12)H(4)N(4), crystallizes with mixed layers of donors and acceptors, with an estimated degree of charge transfer at 0.09 e. In the D (3h)-BTT·C(60)·toluene complex, C(12)H(6)S(3)·C(60)·C(7)H(8), the central ring of BTT is ‘squeezed’ by the C(60) mol­ecules from both faces. However, the degree of charge transfer is low. The C(60) unit is disordered over two sites in a 0.766 (3):0.234 (3) ratio and was refined as a two-component inversion twin.