Band Filling Control by Chemical Approach in Molecular Conductors, (TTM-TTP)M<i>_x</i> Cl₄ [M, M‘ = Fe, Ga, Co, and Mn]

Abstract

TTM-TTP-based 1:1-composition organic conductors with counteranions containing alloyed metals, [TTM-TTP = 2,5-bis[4,5-bis(methylthio)-1,3-dithiol-2-ylidene]-1,3,4,6-tetrathiapentalene; M, M‘ = Fe, Ga, Co, and Mn], have been prepared. The degrees of oxidization of TTM-TTP molecules change with the ratio of monovalent (FeCl4- and GaCl4-) and divalent anions (CoCl42- and MnCl42-). Accordingly, the band filling of the donor HOMO is chemically changed. These salts have the same crystal structure, consisting of one-dimensional uniform donor stacks, and are highly conductive. The conductivity is essentially flat down to 100−200 K, but the room-temperature resistivity and the thermoelectric power systematically increase as the band filling decreases from half filling to empty.