Preparation and functionalization of multilayer fullerenes (carbon nano-onions).

Carbon nano-onions (CNOs) represent a still largely unexplored carbon allotrope. Promising properties of these unique carbon structures are driving the research efforts in this area, but many technical problems remain in their preparation, derivatization, separation and characterization. In this article, we report the preparation, partial purification, and multiple functionalization and solubilization of CNOs.

Azomethine Imines in Four- and Five-Membered Rings: Stable Cyclic Valence Isomers of an α-(Phenyldiazenyl)ketocarbene.

The expected Wolff rearrangement of the ketocarbene intermediate 2, formed upon rhodium(II)-catalyzed elimination of nitrogen from diazoketone 1, does not occur. Instead, by incorporation of the neighboring diazene group the surprisingly stable, crystalline azomethine imines 3 and 4 are formed as cyclic valence isomers of 2. Compound 4, which contains a five-membered ring, is the first representative of a carba-sydnone and can also be obtained by acid-catalyzed isomerization of 3 at 50-70°C.