Tetrathienylethylenes, a New Class of Electron Donors—Dications Twisted by 90° Stabilized by Formation of Polymethine Units

Abstract

With a 90° twist between the two halves, dication 12+ is the first ethylene dication with the maximum distortion possible. The stabilization of the positive charge is achieved in the separate halves of the dication by delocalization over polymethine units. 12+, whose ClO salt melts at about 170°C with decomposition, is obtained from the electrochemical oxidation of 1. The structure of neutral 1 differs substantially from that of its dication.