A Stable Anionic Dithiolene Radical

Sulfurization of anionic N-heterocyclic dicarbene, [:C­{[N­(2,6-Pri2C6H3)]2CHCLi}]n (2), with elemental sulfur (in a 1:2 ratio) in Et2O at low temperature gives 3 by inserting two sulfur atoms into the Li–C (i.e., C2 and C4) bonds in polymeric 2. Further reaction of 3 with 2 equiv of elemental sulfur in THF affords 4• via unexpected C–H bond activation, which represents the first anionic dithiolene radical to be structurally characterized in the solid state. Alternatively, 4• may also be synthesized directly by reaction of 1 with sulfur (in a 1:4 ratio) in THF. Reaction of 4• with GeCl2·dioxane gives an anionic germanium­(IV)–bis­(dithiolene) complex (5). The nature of the bonding in 4• and 5 was probed by experimental and theoretical methods.