A cationic sulfur-hydrocarbon triradical with an excited quartet state

Abstract

The triptycene-bridged tris(thianthrene) compound 1 was designed and synthesized. Three-electron oxidation of 1 by NO[Al(OC(CF₃)₃)₄], followed by crystallization at two different temperatures resulted in the triradical trication salts 2a and 2b respectively, which feature different crystal packing patterns. The triradical trications in 2a and 2b both feature a doublet ground state which can be thermally populated to a quartet state, representing the first examples of cationic main-group triradicals.