1 : 1 composition organic metal including a magnetic counteranion, (TTM-TTP)FeBr1.8Cl2.2

An organic donor, TTM-TTP (TTM-TTP = 2,5-bis[4,5-bis(methylthio)-1,3-dithio lylidene]-1,3,4,6-tetrathiapentalene), forms 1:1 donor/anion salts with FeC l4- and FeBr4-, (TTM-TTP)FeX4(PhCl)(0.5) (X = Cl, Br), which have one-dimen sional dimerized columns and are insulators even at room temperature. In co ntrast, the salt with an alloyed anion, (TTM-TTP)FeBr1.8Cl2.2, shows high e lectrical conductivity of about 1000 S cm(-1) at room temperature and remai ns metallic down to 160 K. This salt has uniform, one-dimensional, donor co lumns. This is the first 1:1 donor/anion composition organic metal with a m agnetic counteranion. These compounds exhibit weak magnetic interactions; t he Weiss temperatures are around 1-3 K.