Synthesis, Properties and Formation of (RCp)Co‐ and (RCp)Rh‐Stabilized[4.8]3Cyclacene Derivatives

Metal‐stabilized belts: A torus, 3, consisting of three four‐ and three eight‐membered conjugated rings and stabilized by (RCp)Co‐ and (RCp)Rh‐ units, was generated by irradiation of [(RCp)Co(CO)2] and [(RCp)Rh(C2H4)2], respectively, and 1. Eleven metal stabilized [4.8]3cyclacene derivatives were synthesized. The substances were prepared in one‐pot reactions by irradiation of a solution of 5,6,11,12‐tetradehydro‐dibenzo[a,e]cyclooctatetraene and the corresponding cobalt reagents or rhodium compounds. The resulting cyclacene derivatives reveal D3h symmetry in solution. In the solid state the hoop shaped systems crystallize in layers, which are intercalated with solvent layers. To unravel the mechanism of the one‐pot reaction we isolated an intermediate, which shows almost planar cyclooctatetraene rings. Metal‐stabilized belts: A torus, 3, consisting of three four‐ and three eight‐membered conjugated rings and stabilized by (RCp)Co‐ and (RCp)Rh‐ units, was generated by irradiation of [(RCp)Co(CO)2] and [(RCp)Rh(C2H4)2], respectively, and 1.