Hexakis(trimethylsilylethynyl)[3]radialene: A Carbon‐Rich Chromophore with Unusual Electronic Properties

Hexaethynyl[3]radialene (1 a) is isoelectronic and isosteric with the known hexacyano[3]radialene and a molecular precursor for a two-dimensional all-carbon network. The hexakis(trimethylsilyl) derivative 1 b was now prepared by addition of tetrachlorocyclopropene to deprotonated 1,5-bis(trimethylsilyl)penta-1,4-diyne, followed by oxidation, and was characterized by X-ray crystallography. In solution, 1 b shows an unexpected purple-red color and is reduced in two reversible one-electron steps to the violet radical anion 1 b and dianion 1 b2−.