By adopting novel Pummerer-cyanation route and by using thionyl chloride as S-transfer reagent, the first thieno[3,4-c]thiophene bearing all electron withdrawing groups (EWGs) has been synthesized. The molecular structure was identified and characterized by ¹H NMR, ¹³C NMR, FTIR spectra, elemental analysis and X-ray diffractional method. The molecular structure of 1,3-dimethoxycarbonyl-4,6-di- cyanothieno[3,4-c]thiophene was calculated by DFT method at B3LYP/6-31G* and B3LYP/6-311＋＋G** levels. The structure, total energy, standard entropy, standard enthalpy and standard free energy were obtained, in which the calculated molecular configuration was very close to the experimental analysis of X-ray diffraction. The data of charge distribution were also used to discuss the stability of the series of nonclassical condensed thieno[3,4-c]thiophene. The calculation results can be better used to explain some experimental phenomena.

Key words: thieno[3,4-c]thiophene, density functional theory, charge distribution, S-transfer reaction, Pummerer-cyanation