Syntheses, structures and properties of phenanthro[1,10-cd:8,9-c′d′]bis[1,2]-dithiole and -diselenole and their methyl and methylthio derivatives as novel electron donors

Abstract

Tetrathio- and tetraseleno-phenanthrenes, as well as their dimethyl and bis(methylthio) derivatives, have been synthesized as the first examples of novel electron donors of the peri-dichalcogen-bridged polyphene type. X-Ray analyses have revealed that these compounds have planar heterocyclic structures similar to that of perylene, in the crystal, the molecules are stacked in columns with strong interactions between the heteroatoms in adjacent columns, which produces a two- or three-dimensional interactive network of the molecular components. Cyclic voltammetry studies have indicated that these compounds have somewhat weaker electron-donating abilities than do their anthracene counterparts bearing structural resemblances. Although only tetraselenophenanthrene gave a conductive chargetransfer complex with 7,7,8,8-tetracyanoquinodimethane (TCNQ), they all formed complexes with stronger electron acceptors, 2,3,5,6-tetrafluoro-TCNQ (TCNQF₄) and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), giving rare examples of conductive materials containing TCNQF₄ and DDQ. In addition, they formed a variety of radical cation salts, which are also highly conductive.