The Many Faces of ET

Abstract

Abstract A major feature of the ET molecule is its ability to form many different phases and structures with the same or different anions. Whilst this considerably complicates the growth and characterisation of these materials this does allow a systematic study of compounds differing only in charge state or crystal structure, but otherwise containing the same donor and acceptor species. We show that ET forms at least four different phases with the ReO4 −anion, allowing such a systematic study. We show that one of these, γ-ET3(ReO4)2, is the only currently known example of an ET charge transfer salt in which the anions are not ordered at room temperature. We find the anions become ordered at a lower temperature. We show that anions smaller than some certain value stabilise a single phase containing 3 ET molecules for every two anions and that larger anions form different sets of crystal structures.