A Methyl Substituted Thiophenic-TTF Donor and its Salts

-methyldithiophene-tetrathiafulvalene (-mDT-TTF), the first alkyl substituted thiophenic-TTF electronic donor, as well as some of its charge transfer salts are reported. The crystal structure of -mDT-TTF is composed of molecular stacks aligned parallel to each other. Its cyclic voltammetry shows higher electron donor ability than the unsubstituted analogue -DT-TTF. This material has been employed as a semiconductor in an organic field effect transistor, giving a mobility of 4x10 cm/Vs. Two charge transfer salts of this donor with [M(mnt)2] anions (mnt=maleonitriledithiolate), with M=Co and Au, were obtained by electrocrystallization presenting unusual stoichiometries: (-mDT-TTF)[Co(mnt)2] (2) and (-mDT-TTF)3[Au(mnt)2]2 (3). In the cobalt compound the donor molecules are fully oxidized and the Co complex is dimerized presenting a semiconducting behavior (7x10 S/cm). The gold compound is composed by alternated stacks of donor trimers and pairs of anions.