Syntheses and Crystal Structures of DBTTF Derivatives Substituted Unsymmetrically by Electron Donating Groups: (MeO)2(MDO) DBTTF, (EDO) (MDO) DBTTF and (MeO)2(EDO) DBTTF

Three novel unsymmetrically substituted DBTTF derivatives, (MeO) 2 (MDO) DBTTF, (EDO) (MDO) DBTTF, and (MeO) 2 (EDO) DBTTF, have been synthesized and their physicochemical properties are elucidated. Here, MeO, MDO, and EDO mean methoxy, methylenedioxy, and ethylenedioxy groups, respectively. Trimethylaluminum is found to be suitable for the syntheses of the above DBTTF derivatives using the non-coupling method. MDO is rather an effective substituent in reducing the difference between the first and the second redox potentials. The crystal structures of (MeO) 2 (MDO) DBTTF and (MeO) 2 (EDO) DBTTF were analyzed by an X-ray crystal structure analysis. In the crystal of (MeO) 2 (MDO) DBTTF, two molecules form a face-to-face pair, in which two molecules arrange so as to cancel their dipole moments to each other. The molecules of (MeO) 2 (EDO) DBTTF form a herringbone column structure in the crystal. Intermolecular short S··S atomic contacts are not found in the crystals of (MeO) 2 (MDO) DBTTF and (MeO) 2 (EDO) DBTTF. However, intermolecular interactions through C··C and C··O atomic contacts, and hydrogen bondings are recognized.