A Methyl‐Substituted Thiophene–Tetra­thiafulvalene Donor and Its Salts

Abstract

α‐Methyldithiophene–tetrathiafulvalene (α‐mDT‐TTF), the first alkyl‐substituted thiophene–tetrathiafulvalene electronic donor, and some of its charge‐transfer salts were explored. The crystal structure of α‐mDT‐TTF is composed of molecular stacks aligned parallel to each other. Its cyclic voltammetry shows higher electron‐donor ability than the unsubstituted analogue. This material was employed as a semiconductor in an organic field‐effect transistor and showed a mobility of 4 × 10–4 cm2 V–1 s–1. Two charge‐transfer salts of this donor with [M(mnt)2]– anions (mnt = maleonitriledithiolate), M = Co and Au, were obtained by electrocrystallization; they present unusual stoichiometries: (α‐mDT‐TTF)[Co(mnt)2] and (α‐mDT‐TTF)3[Au(mnt)2]2. In the cobalt compound, the donor molecules are fully oxidized and the Co complex is dimerized; it presents semiconducting behavior (7 × 10–3 S cm–1). The gold compound is composed of alternating stacks of donor trimers and pairs of anions.