Abstract
The developments of novel electron donors of non-TTF types are described, especially focussing on peri-condensed heteroarenes bearing a structural resemblance to pyrene or perylene and on peri-dichalcogen bridged arenes like tetrathiotetracene. These compounds have been designed chiefly to provide strong donating abilities and strong intermolecular heteroatomic contacts, which are prerequisites for components of organic metals. As a result, some of them have stronger donating abilities than does tetrathiafulvalene (TTF), thus providing a large number of highly conducting molecular complexes.