Electrochemical synthesis of bis(2-thienyl)silanes, 2-thienylchlorosilanes, bis[5-(2-bromothienyl)]silanes, and 5-(2-bromothienyl) dimethylchlorosilane, precursors of poly[(silanylene)thiophene]s

Bis(2-thienyl)silanes and bis[5-(2-bromothienyl)]silanes were synthesized by electrochemical reduction of monohalothiophenes (Br,CI) and 2,5-dibromothiophene respectively in the presence of a dichlorosilane in THF or DME, using an undivided cell, a sacrificial Mg or Al anode, a constant current density and tetrabutylammonium bromide as the supporting electrolyte. In addition, when dichlorosilanes were used in large excess, halothiophenes underwent solely a monocoupling reaction leading selectively to thienylchlorosilanes, which reveals the versatility of the electrochemical method.