Pentacene (C22H14) has played an essential role in functional organic electronic devices. It is considered a representative of the most active small-molecule semiconductor materials due to high charge carrier mobility. Furthermore, it is expected that sophisticated design of pentacene-based scaffolds as well as their doping with alkali metals may lead to a novel class of superconducting materials. For these reasons, pentacene has attracted our attention as an interesting linear polyaromatic ligand for chemical reduction and coordination chemistry studies. Herein we investigated the reduction behavior of pentacene with all Group 1 metals, ranging from Li to Cs. As a result, an extended family of the doubly-reduced pentacene anions has been isolated with the corresponding alkali metal countercations and characterized structurally and spectroscopically. The different coordination mode of the smallest Li+ ion vs. the heavier Group 1 congeners has been demonstrated. In addition, the use of benzo-15-crown-5 ether in the Na-induced reduction allowed the isolation of the first "naked" pentacene dianion. The X-ray crystallographic study of these organometallic complexes revealed a pentacene core deformation, details on metal ion coordination and unique solid-state assemblies. These studies could facilitate further development of the alkali-metal doped pentacene materials for practical applications.

Chemical reduction of pentacene with alkali metals: From Li to Cs

ACS Fall 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.