Crystal and molecular structure of a charge-transfer complex between α,α′-dimethylquaterthiophene and 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane

Abstract

A 1:1 stoichiometric charge-transfer (CT) complex between α,α′-dimethylquaterthiophene (DMQtT) and 2,3,5,6,-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (TCNQF 4) crystallizes in the triclinic system with the space group P 1, a = 10.185(6) , b = 10.568(5), c=6.842(3) A ̊ , α=98.92(4), β=95.89(4), γ=67.24(4)°, Z=1, U=670.1 A ̊ 3 and D c = 1.573 g cm −3. The crystals comprise alternate mixed columns of DMQtT and TCNQF 4 with their molecular planes nearly parallel, this structural feature being characteristic of weak CT complexes. The crystal structure is compared with that of a related CT complex of non-substituted quaterthiophene and 7,7,8,8-tetracyanoquinodimethane (TCNQ) and the substituent effect on the crystal structure is discussed. The molecular structures of DMQtT and TCNQF 4 in the CT and neutral forms are also compared.